add bullet for changing which version is shown in readthedocs.org

.gitlab/issue_templates/release.md

@@ -11,3 +11,4 @@
 * [ ] commit (signed)
 * [ ] create signed tag (`git tag -s 0.2.0 -m 'Release 0.2.0'`)
 * [ ] Push to MR, including tag
+* [ ] Log into readthedocs.org and update documentation for tagged versions