Added changelog and updated readme

CHANGELOG.md

+v0.22
+-----
+
+* libgit2 types revealed through the libqgit2 API renamed as needed.
+* Removed the Push object and Repository::push() method. They got
+  replaced by the Remote::push() method.
+* A slight behavioral change in Repository::fetch() method when no
+  refspecs are given: previously all branches were fetched. Now the
+  fetch refspecs configured for the remote are used.

README.md

@@ -3,15 +3,20 @@ libqgit2
 
 A Qt/C++ wrapper for libgit2
 
-Official repository is https://projects.kde.org/projects/playground/libs/libqgit2/repository/
+Official repository is
+https://projects.kde.org/projects/playground/libs/libqgit2/repository/
 
-Feel free to fork this repository to play with the library but remember it is not the official one.
+Feel free to fork this repository to play with the library but remember
+it is not the official one.
 
-libqgit2 uses libgit2 version 0.20.0.
+The version number follows that of libgit2: libqgit2 0.21.x uses libgit2
+0.21.x and libqgit2 0.22.x uses libgit2 0.22.x and so on.
 
 Compiler warnings
 =================
 
-Currently, compiler complains with the use of QSharedPointer on opaque libgit structures.
-This is a known issue of Qt4 that has already been fixed in Qt5, see [this report](https://codereview.qt-project.org/#change,26974).
-I'm going to keep the QSharedPointer stuff by now, I'll replace it only if problems arise.
+Currently, compiler complains with the use of QSharedPointer on opaque
+libgit structures. This is a known issue of Qt4 that has already been
+fixed in Qt5, see [this report](https://codereview.qt-project.org/#change,26974).
+I'm going to keep the QSharedPointer stuff by now, I'll replace it only
+if problems arise.