diff -r bbd2364fbf71 -r 439fc5d13c41 CONTRIBUTING.md
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/CONTRIBUTING.md	Fri Jun 15 16:30:06 2018 +0300
@@ -0,0 +1,21 @@
+How Do I Submit A Good Pull Request?
+----------------------------------
+
+It's highly recommended to write nice and clean python code. Beremiz
+project tries to follows most of PEP-8 recommendations. They are
+automatically checked on every push and merge by Bitbucket pipelines.
+
+To avoid pushing "unclean" code, i's recommended to add one of the following
+commands to pre commit Mercurial hook into .hg/hgrc configuration file.
+
+```
+[hooks]
+pretxncommit.linter = ./tests/tools/check_source.sh --only-changes
+```
+or the same done using Docker container, so result will be the same as
+on Bitbucket pipeline.
+
+```
+[hooks]
+pretxncommit.linter = hg status -m -n -a -n -I '**.py' --change $HG_NODE > files.lst && docker run --volume=$PWD:/beremiz --workdir="/beremiz" --volume=$PWD/../CanFestival-3:/CanFestival-3 --memory=1g --entrypoint=/beremiz/tests/tools/check_source.sh skvorl/beremiz-requirements --files-to-check files.lst
+```