:memo: add more API documentation

doc/docset/docSet.sql

diff --git a/doc/docset/docSet.sql b/doc/docset/docSet.sql
index 47d893e..0c32335 100644
--- a/doc/docset/docSet.sql
+++ b/doc/docset/docSet.sql
@@ -32,7 +32,12 @@
 INSERT INTO searchIndex(name, type, path) VALUES ('exception', 'Class', 'api/basic_json/exception/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('find', 'Method', 'api/basic_json/find/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('flatten', 'Method', 'api/basic_json/flatten/index.html');
+INSERT INTO searchIndex(name, type, path) VALUES ('from_bson', 'Function', 'api/basic_json/from_bson/index.html');
+INSERT INTO searchIndex(name, type, path) VALUES ('from_cbor', 'Function', 'api/basic_json/from_cbor/index.html');
+INSERT INTO searchIndex(name, type, path) VALUES ('from_msgpack', 'Function', 'api/basic_json/from_msgpack/index.html');
+INSERT INTO searchIndex(name, type, path) VALUES ('from_ubjson', 'Function', 'api/basic_json/from_ubjson/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('front', 'Method', 'api/basic_json/front/index.html');
+INSERT INTO searchIndex(name, type, path) VALUES ('get', 'Method', 'api/basic_json/get/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('get_allocator', 'Function', 'api/basic_json/get_allocator/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('input_format_t', 'Enum', 'api/basic_json/input_format_t/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('insert', 'Method', 'api/basic_json/insert/index.html');
@@ -89,10 +94,6 @@
 INSERT INTO searchIndex(name, type, path) VALUES ('type_name', 'Method', 'api/basic_json/type_name/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('unflatten', 'Method', 'api/basic_json/unflatten/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('update', 'Method', 'api/basic_json/update/index.html');
-INSERT INTO searchIndex(name, type, path) VALUES ('from_bson', 'Function', 'api/basic_json/from_bson/index.html');
-INSERT INTO searchIndex(name, type, path) VALUES ('from_cbor', 'Function', 'api/basic_json/from_cbor/index.html');
-INSERT INTO searchIndex(name, type, path) VALUES ('from_msgpack', 'Function', 'api/basic_json/from_msgpack/index.html');
-INSERT INTO searchIndex(name, type, path) VALUES ('from_ubjson', 'Function', 'api/basic_json/from_ubjson/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('to_bson', 'Function', 'api/basic_json/to_bson/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('to_cbor', 'Function', 'api/basic_json/to_cbor/index.html');
 INSERT INTO searchIndex(name, type, path) VALUES ('to_msgpack', 'Function', 'api/basic_json/to_msgpack/index.html');

doc/mkdocs/docs/api/basic_json/get.md

diff --git a/doc/mkdocs/docs/api/basic_json/get.md b/doc/mkdocs/docs/api/basic_json/get.md
new file mode 100644
index 0000000..7154109
--- /dev/null
+++ b/doc/mkdocs/docs/api/basic_json/get.md
@@ -0,0 +1,97 @@
+# basic_json::get
+
+```cpp
+// (1)
+template<typename ValueType>
+ValueType get() const noexcept(
+    noexcept(JSONSerializer<ValueType>::from_json(
+        std::declval<const basic_json_t&>(), std::declval<ValueType&>())));
+
+// (2)
+template<typename BasicJsonType>
+BasicJsonType get() const;
+```
+
+1. Explicit type conversion between the JSON value and a compatible value which is
+   [CopyConstructible](https://en.cppreference.com/w/cpp/named_req/CopyConstructible) and
+   [DefaultConstructible](https://en.cppreference.com/w/cpp/named_req/DefaultConstructible). The value is converted by
+   calling the `json_serializer<ValueType>` `from_json()` method.
+   
+    The function is equivalent to executing
+    ```cpp
+    ValueType ret;
+    JSONSerializer<ValueType>::from_json(*this, ret);
+    return ret;
+    ```
+
+    This overloads is chosen if:
+    
+    - `ValueType` is not `basic_json`,
+    - `json_serializer<ValueType>` has a `from_json()` method of the form
+      `void from_json(const basic_json&, ValueType&)`, and
+    - `json_serializer<ValueType>` does not have a `from_json()` method of the form
+      `ValueType from_json(const basic_json&)`
+
+    If the type is **not** [CopyConstructible](https://en.cppreference.com/w/cpp/named_req/CopyConstructible) and
+    **not** [DefaultConstructible](https://en.cppreference.com/w/cpp/named_req/DefaultConstructible), the value is
+    converted by calling the `json_serializer<ValueType>` `from_json()` method.
+   
+    The function is then equivalent to executing
+    ```cpp
+    return JSONSerializer<ValueTypeCV>::from_json(*this);
+    ``` 
+   
+    This overloads is chosen if:
+    
+    - `ValueType` is not `basic_json` and
+    - `json_serializer<ValueType>` has a `from_json()` method of the form
+     `ValueType from_json(const basic_json&)`
+
+    If `json_serializer<ValueType>` has both overloads of `from_json()`, the latter one is chosen.
+
+2. Overload for `basic_json` specializations. The function is equivalent to executing
+    ```cpp
+    return *this;
+    ``` 
+
+## Template parameters
+
+`ValueType`
+:   the value type to return
+
+`BasicJsonType`
+:   a specialization of `basic_json`
+
+## Return value
+
+1. copy of the JSON value, converted to `ValueType`
+2. a copy of `#!cpp *this`, converted into `BasicJsonType`
+
+## Exceptions
+
+Depends on what `json_serializer<ValueType>` `from_json()` method throws
+
+## Example
+
+??? example
+
+    The example below shows several conversions from JSON values
+    to other types. There a few things to note: (1) Floating-point numbers can
+    be converted to integers, (2) A JSON array can be converted to a standard
+    `std::vector<short>`, (3) A JSON object can be converted to C++
+    associative containers such as `std::unordered_map<std::string, json>`.
+        
+    ```cpp
+    --8<-- "examples/get__ValueType_const.cpp"
+    ```
+    
+    Output:
+    
+    ```json
+    --8<-- "examples/get__ValueType_const.output"
+    ```
+
+## Version history
+
+1. Since version 2.1.0.
+2. Since version 2.1.0. Extended to work with other specializations of `basic_json` in version 3.2.0.

doc/mkdocs/docs/api/basic_json/index.md

diff --git a/doc/mkdocs/docs/api/basic_json/index.md b/doc/mkdocs/docs/api/basic_json/index.md
index 55851ab..5825177 100644
--- a/doc/mkdocs/docs/api/basic_json/index.md
+++ b/doc/mkdocs/docs/api/basic_json/index.md
@@ -135,7 +135,7 @@
 
 Direct access to the stored value of a JSON value.
 
-- get - get a value
+- [**get**](get.md) - get a value
 - get_to - get a value
 - get_ptr - get a pointer value
 - get_ref - get a reference value

doc/mkdocs/mkdocs.yml

diff --git a/doc/mkdocs/mkdocs.yml b/doc/mkdocs/mkdocs.yml
index 115bfbd..caeb812 100644
--- a/doc/mkdocs/mkdocs.yml
+++ b/doc/mkdocs/mkdocs.yml
@@ -106,6 +106,7 @@
         - api/basic_json/from_msgpack.md
         - api/basic_json/from_ubjson.md
         - api/basic_json/front.md
+        - api/basic_json/get.md
         - api/basic_json/get_allocator.md
         - api/basic_json/input_format_t.md
         - api/basic_json/insert.md