[Changelog] Add entry about specifying sources in the Podfile by URL

CHANGELOG.md

@@ -4,6 +4,28 @@ To install or update CocoaPods see this [guide](http://docs.cocoapods.org/guides
 
 ## Master
 
+##### Breaking
+
+* Add support for loading podspecs from specific spec-repos _only_,
+  a.k.a. ‘sources’. By default, when not specifying any specific sources in your
+  Podfile, all source repos will be used, as has always been the case.
+  This implicit use of sources is, however, now deprecated.
+  However, once you specify specific sources, **no** repos wil be included by
+  default. For example:
+
+        source 'https://banana.com/corp/private-spec-repo.git'
+        source 'https://github.com/CocoaPods/Specs.git'
+
+  Any source URLs specified that have not yet been added will be cloned before
+  resolution begins.  
+  [François Benaiteau](https://github.com/netbe)
+  [Fabio Pelosin](https://github.com/fabiopelosin)
+  [Samuel Giddins](https://github.com/segiddins)
+  [#1143](https://github.com/CocoaPods/CocoaPods/pull/1143)
+  [Core#19](https://github.com/CocoaPods/Core/pull/19)
+  [Core#170](https://github.com/CocoaPods/Core/issues/170)
+  [#2515](https://github.com/CocoaPods/CocoaPods/issues/2515)
+
 ##### Bug Fixes
 
 * Fixes the detection of JSON podspecs included via `:path`.
@@ -20,7 +42,7 @@ To install or update CocoaPods see this [guide](http://docs.cocoapods.org/guides
   [Kyle Fuller](https://github.com/kylef)
   [#2147](https://github.com/CocoaPods/CocoaPods/issues/2147)
 
-* Fixes an issue where `pod init` would not add `source 'master'` to newly 
+* Fixes an issue where `pod init` would not add `source 'master'` to newly
   created Podfiles.  
   [Ash Furrow](https://github.com/AshFurrow)
   [#2473](https://github.com/CocoaPods/CocoaPods/issues/2473)
@@ -46,7 +68,7 @@ To install or update CocoaPods see this [guide](http://docs.cocoapods.org/guides
   [Fabio Pelosin](https://github.com/fabiopelosin)
   [#1143](https://github.com/CocoaPods/CocoaPods/pull/1143)
   [Core#19](https://github.com/CocoaPods/Core/pull/19)
-  
+
 * The `Pods` directory has been reorganized. This might require manual
   intervention in projects where files generated by CocoaPods have manually been
   imported into the user's project (common with the acknowledgements files).