Add a template for "Merge versioned content" issues (#1915)

Author: NickVolynkin

.github/ISSUE_TEMPLATE/versions.md

@@ -0,0 +1,27 @@
+---
+name: Merge versioned content
+about: Merge versioned content into latest branch
+title: "[0pt] Merge version 2.x.y into latest"
+labels: 
+assignees: 
+---
+# Merge version 2.x.y into latest
+
+# What needs to be done
+
+**Reviewer:** @NickVolynkin
+
+# Definition of done
+
+- [ ] For each element in version's changelog add a "Read more" link to the docs.
+- [ ] In the target docs make a "Since version 2.x.y" statement
+      with link back to release notes.
+- [ ] When there are alternatives for the same action,
+      move forward the one which is implemented in a later version.
+
+
+# Planning checklist
+
+- [ ] Add to Documentation board
+- [ ] Add milestone "Merge 2.x branches"
+- [ ] Evaluate in storypoints