Add changelog for version 1.2.2

Author: frou

docs/packagecontrol_changelogs/1.2.2.txt

@@ -0,0 +1,6 @@
+-> 1.2.2
+
+FIXED:
+
+- Improved usability and reliability of [Prev] button that steps back through
+  multiple previous commits that affected a single line.

messages.json

@@ -1,4 +1,5 @@
 {
   "1.2.0": "docs/packagecontrol_changelogs/1.2.0.txt",
-  "1.2.1": "docs/packagecontrol_changelogs/1.2.1.txt"
+  "1.2.1": "docs/packagecontrol_changelogs/1.2.1.txt",
+  "1.2.2": "docs/packagecontrol_changelogs/1.2.2.txt"
 }