updating how_to_contribute.md and removing version control chapter. (#521)

* updating how_to_contribute.md and removing version control chapter.

* linking code style guide

Author: leios

SUMMARY.md

@@ -3,7 +3,6 @@
 * [Algorithm Archive](README.md)
 * [Introduction](contents/introduction/introduction.md)
 * [How To Contribute](contents/how_to_contribute/how_to_contribute.md)
-* [Version Control](contents/git_and_version_control/git_and_version_control.md)
 * [Data Structures](contents/data_structures/data_structures.md)
     * [Stacks and Queues](contents/stacks_and_queues/stacks_and_queues.md)
 * [Mathematical Background](contents/mathematical_background/mathematical_background.md)