AAPT2: Update version and readme

Update version to 2.2 and update readme to reflect added
support for inline complex XML resources.

Change-Id: If825c96541952e95860d34390c6c36704a24129b
diff --git a/tools/aapt2/Main.cpp b/tools/aapt2/Main.cpp
index ed55f85..f3f70d6 100644
--- a/tools/aapt2/Main.cpp
+++ b/tools/aapt2/Main.cpp
@@ -25,7 +25,7 @@
 static const char* sMajorVersion = "2";
 
 // Update minor version whenever a feature or flag is added.
-static const char* sMinorVersion = "1";
+static const char* sMinorVersion = "2";
 
 int printVersion() {
     std::cerr << "Android Asset Packaging Tool (aapt) "