Merge "Deprecate $wgExternalDiffEngine = 'wikidiff2'"

diff --combined RELEASE-NOTES-1.32
index 0497531,abd9f89..e24ab83
--- 1/RELEASE-NOTES-1.32
--- 2/RELEASE-NOTES-1.32
+++ b/RELEASE-NOTES-1.32
@@@ -65,8 -65,6 +65,8 @@@ production
  * Updated wikimedia/scoped-callback from 1.0.0 to 2.0.0.
  ** ScopedCallback objects can no longer be serialized.
  * Updated wikimedia/wrappedstring from 2.3.0 to 3.0.1.
 +* Updated mediawiki/mediawiki-codesniffer from v20.0.0 to v21.0.0.
 +* Updated composer/spdx-licenses from 1.3.0 to 1.4.0.
  
  ==== New external libraries ====
  * Added wikimedia/xmp-reader 0.5.1
@@@ -289,6 -287,8 +289,8 @@@ because of Phabricator reports
    mNewPage, mOldContent, mNewContent, mRevisionsLoaded, mTextLoaded and
    mCacheHit is deprecated. Use getOldid() / getNewid() for the first two,
    do your own lookup for page/content. mNewRev / mOldRev remains public.
+ * The $wgExternalDiffEngine value 'wikidiff2' is deprecated. To use wikidiff2
+   just enable the PHP extension, and it will be autodetected.
  
  === Other changes in 1.32 ===
  * (T198811) The following tables have had their UNIQUE indexes turned into