provider-decoder.pod: Documentation of provider side decoder API

Fixes #13949

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14756)
diff --git a/doc/build.info b/doc/build.info
index 48730cf..7ac0890 100644
--- a/doc/build.info
+++ b/doc/build.info
@@ -4272,6 +4272,10 @@
 GENERATE[html/man7/provider-cipher.html]=man7/provider-cipher.pod
 DEPEND[man/man7/provider-cipher.7]=man7/provider-cipher.pod
 GENERATE[man/man7/provider-cipher.7]=man7/provider-cipher.pod
+DEPEND[html/man7/provider-decoder.html]=man7/provider-decoder.pod
+GENERATE[html/man7/provider-decoder.html]=man7/provider-decoder.pod
+DEPEND[man/man7/provider-decoder.7]=man7/provider-decoder.pod
+GENERATE[man/man7/provider-decoder.7]=man7/provider-decoder.pod
 DEPEND[html/man7/provider-digest.html]=man7/provider-digest.pod
 GENERATE[html/man7/provider-digest.html]=man7/provider-digest.pod
 DEPEND[man/man7/provider-digest.7]=man7/provider-digest.pod
@@ -4419,6 +4423,7 @@
 html/man7/provider-asym_cipher.html \
 html/man7/provider-base.html \
 html/man7/provider-cipher.html \
+html/man7/provider-decoder.html \
 html/man7/provider-digest.html \
 html/man7/provider-encoder.html \
 html/man7/provider-kdf.html \
@@ -4521,6 +4526,7 @@
 man/man7/provider-asym_cipher.7 \
 man/man7/provider-base.7 \
 man/man7/provider-cipher.7 \
+man/man7/provider-decoder.7 \
 man/man7/provider-digest.7 \
 man/man7/provider-encoder.7 \
 man/man7/provider-kdf.7 \