Merge branch 'docs-add-redirect-editor-lite' into 'master'

Add redirect for moved doc

See merge request gitlab-org/gitlab!64459

doc/development/fe_guide/editor_lite.md

+---
+redirect_to: 'source_editor.md'
+remove_date: '2021-09-19'
+---
+
+This document was moved to [another location](source_editor.md).
+
+<!-- This redirect file can be deleted after <2021-09-19>. -->
+<!-- Before deletion, see: https://docs.gitlab.com/ee/development/documentation/#move-or-rename-a-page -->