Add CHANGES and release note for [GL #3795]

CHANGES

@@ -1,3 +1,9 @@
+6072.	[bug]		Avoid the OpenSSL lock contention when initializing
+			Message Digest Contexts by using explicit algorithm
+			fetching, initializing static contexts for every
+			supported algorithms, and initializing the new context
+			by copying the static copy. [GL #3795]
+
 6071.	[func]		The use of "port" when configuring query-source,
 			transfer-source, notify-source and parental-source
 			addresses has been deprecated, along with the

doc/notes/notes-current.rst

@@ -55,6 +55,9 @@ Bug Fixes
   cause increased memory consumption due to delayed cleaning of view memory.
   This has been fixed. :gl:`#3801`
 
+- Improve the speed of the message digest algorithms (MD5, SHA-1,
+  SHA-2) and NSEC3 hashing. :gl:`#3795`
+
 Known Issues
 ~~~~~~~~~~~~