Add file .git-blame-ignore-revs

This file contains hashes of commits that should be ignored with
'git ignore'.

You can ignore commits specified there automatically by running
$ git config blame.ignoreRevsFile .git-blame-ignore-revs

.git-blame-ignore-revs

@@ -0,0 +1,10 @@
+# git blame ignore list
+#
+# This file contains git hashes of commits to be ignored by git blame.
+# These commits are considered not important (in means of "they don't
+# change any code logic/abstract syntax tree").
+#
+# - Only large global changes should be added to this list.
+# - Add comment above every commit hash, preferably with timestamp,
+#   author and commit title.
+# - Append new hashes to the bottom; keep the list chronological.

README.md

@@ -35,6 +35,14 @@ PYTHONPATH=./src python -m subscription_manager.scripts.rct
 
 (You can also just export `PYTHONPATH` instead of setting it in each command).
 
+To ignore bulk commits that only change the format of the code, not the code
+itself (e.g. `black`ing whole codebase), add `.git-blame-ignore-revs` to your
+git configuration:
+
+```bash
+git config blame.ignoreRevsFile .git-blame-ignore-revs
+```
+
 Pipenv
 ------