Add info about end of support for OpenSSL <3.0

Author: jacekwegr

CHANGELOG.md

@@ -33,9 +33,10 @@
 - Documentation improvements (#4476, #4487, #4488)
 - CI improvements (#4459)
 
-## Known issues
+## Known issues and upgrade recommendations
 - If you are using MongooseIM 4.1.0 to 6.3.1 with SCRAM authentication and OpenSSL >=3.4.1, hashes for algorithms stronger than SHA-1 are calculated incorrectly.
 This issue is fixed in this release. See [SCRAM hashing issue](/doc/developers-guide/SCRAM-serialization.md#scram-hash-calculation-issue-in-mongooseim-410631) for details and required actions.
+- OpenSSL versions below 3.0 are no longer supported. If you are using OpenSSL 1.x or older, you must upgrade to OpenSSL 3.x before updating MongooseIM, as older versions will not work.
 
 ## Commits, merged PRs and closed issues
 - [List of merged PRs](https://github.com/esl/MongooseIM/pulls?q=is%3Apr+is%3Amerged+milestone%3A6.3.2)

doc/migrations/6.3.1_6.3.2.md

@@ -88,8 +88,11 @@ Migration scripts for CockroachDB, PostgreSQL, MySQL, and MS SQL are available i
 
 System message translations are now handled by [`service_translations`](../configuration/Services.md#service_translations). Translations files can be found in [`priv/translations/`](https://github.com/esl/MongooseIM/tree/master/priv/translations/).
 
-### SCRAM hashing fix
+## SCRAM hashing fix
 
 In versions 6.3.1 and earlier, a bug caused incorrect hash calculations for SCRAM authentication when using algorithms stronger than SHA-1 with OpenSSL >=3.4.1.
 This release includes a fix for this issue. If you were affected, all users must reset their passwords after upgrading to ensure correct authentication.
 For more details, see [SCRAM hashing issue](../developers-guide/SCRAM-serialization.md#scram-hash-calculation-issue-in-mongooseim-410631).
+
+## OpenSSL <3.0 no longer supported
+All OpenSSL versions below 3.0 are no longer supported. If your deployment relies on OpenSSL 1.x or older, you must upgrade to OpenSSL 3.x before updating MongooseIM, as older versions will not work.