Merge branch 'kcj-add-philosophy' into 'master'

Adds a PHILOSOPHY.md

See merge request gitlab-org/gitlab-ce!23200

PHILOSOPHY.md

+This document is intended to communicate the product philosophy GitLab uses in creating GitLab Community Edition. The principles can be found in the [Product Section of the GitLab Handbook](https://about.gitlab.com/handbook/product/#product-at-gitlab).
\ No newline at end of file

changelogs/unreleased/kcj-add-philosophy.yml

+---
+title: Adds a PHILOSOPHY.md which references GitLab Product Handbook
+merge_request: 23200
+author:
+type: other