Added info about the purpose of this document
# Development guide
-This file contains guidelines for both groups: core developers
- and occasional contributors.
+This file contains guidelines for both groups: core developers and occasional contributors.
+The purpose is to have a reference point and summary of various design discussions the team has.
+It makes it easy to build high quality product if we create, update and consistently follow high level guidelines.
+Doing code review is faster if we can reference clear guidelines rather than explaining the same principle again and again.
+
+Below are **guidelines**!
+They are not set in stone.
+Please suggest changes or add other important guidelines.
+Be pragmatic, all rules have exceptions given good reasons.
## Dependencies on external libraries
