Merge "Document external libraries changes in release notes"

diff --cc RELEASE-NOTES-1.25
index 8f6aaca,21d3c88..92e0a2c
--- 1/RELEASE-NOTES-1.25
--- 2/RELEASE-NOTES-1.25
+++ b/RELEASE-NOTES-1.25
@@@ -59,15 -59,36 +59,40 @@@ production
  * Added a hook, "ApiOpenSearchSuggest", to allow extensions to provide extracts
    and images for ApiOpenSearch output. The semantics are identical to the
    "OpenSearchXml" hook provided by the OpenSearchXml extension.
 +* PrefixSearchBackend hook now has an $offset parameter. Combined with $limit,
 +  this allows for pagination of prefix results. Extensions using this hook
 +  should implement supporting behavior. Not doing so can result in undefined
 +  behavior from API clients trying to continue through prefix results.
  
+ ==== External libraries ====
+ * MediaWiki now requires certain external libraries to be installed. In the past
+   these were bundled inside the git repository of MediaWiki core, but now they
+   need to be installed separately. For users using the tarball, this will be taken
+   care of and no action will be required. Users using git will either need to use
+   composer to fetch dependencies or use the mediawiki/vendor repository which includes
+   all dependencies for MediaWiki core and ones used in Wikimedia deployment. Detailed
+   instructions can be found at <https://www.mediawiki.org/wiki/Download_from_Git#Fetch_external_libraries>.
+ * The following libraries are now required:
+ ** psr/log 1.0.0
+ *** This library provides the interfaces set by the PSR-3 standard (<http://www.php-fig.org/psr/psr-3/>)
+     which are used by MediaWiki interally by the MWLogger class.
+ *** See the structured logging RfC (<https://www.mediawiki.org/wiki/Requests_for_comment/Structured_logging>)
+     for more background information.
+ ** cssjanus/cssjanus 1.1.1
+ *** This library was formerly bundled with MediaWiki core and has now been removed. It automatically
+     flips CSS for RTL support.
+ ** leafo/lessphp 0.5.0
+ *** This library was formerly bundled with MediaWiki core and has now been removed. It compiles LESS
+     files into CSS.
+ ** cdb/cdb 1.0.0
+ *** This library was formerly a part of MediaWiki core, and has now been split out into a separate library.
+     It provides CDB functions which are used in the Interwiki and Localization caches. More information
+     about the library can be found at <https://www.mediawiki.org/wiki/CDB>.
+ 
  === Bug fixes in 1.25 ===
 -* (bug 71003) No additional code will be generated to try to load CSS-embedded
 +* (T73003) No additional code will be generated to try to load CSS-embedded
    SVG images in Internet Explorer 6 and 7, as they don't support them anyway.
 -* (bug 67021) On Special:BookSources, corrected validation of ISBNs (both
 +* (T69021) On Special:BookSources, corrected validation of ISBNs (both
    10- and 13-digit forms) containing "X".
  * Page moving was refactored into a MovePage class. As part of that:
  ** The AbortMove hook was removed.