-N option to diff is not essential, and mentioning it is unnecessarily
confusing to people whose diff doesn't implement it.

README

diff --git a/README b/README
index 320ac1b..7e3e93b 100644
--- a/README
+++ b/README
@@ -174,4 +174,4 @@
  # [your changes]
  # ./Configure dist; make clean
  # cd ..
- # diff -urN openssl-orig openssl-work > mydiffs.patch
+ # diff -ur openssl-orig openssl-work > mydiffs.patch