Update cheatsheets

git-check-ref-format

@@ -0,0 +1,21 @@
+---
+syntax: markdown
+tags: [tldr, common]
+source: https://github.com/tldr-pages/tldr.git
+---
+# git check-ref-format
+
+> Check if a reference name is acceptable, and exit with a non-zero status if it is not.
+> More information: <https://git-scm.com/docs/git-check-ref-format>.
+
+- Check the format of the specified reference name:
+
+`git check-ref-format {{refs/head/refname}}`
+
+- Print the name of the last branch checked out:
+
+`git check-ref-format --branch @{-1}`
+
+- Normalize a refname:
+
+`git check-ref-format --normalize {{refs/head/refname}}`