git-stripspace: add page (#5094)

pages/common/git-stripspace.md

@@ -0,0 +1,16 @@
+# git stripspace
+
+> Read text (e.g. commit messages, notes, tags, and branch descriptions) from the standard input and clean it into the manner used by Git.
+> More information: <https://git-scm.com/docs/git-stripspace>.
+
+- Trim whitespace from a file:
+
+`cat {{path/to/file}} | git stripspace`
+
+- Trim whitespace and Git comments from a file:
+
+`cat {{path/to/file}} | git stripspace --strip-comments`
+
+- Convert all lines in a file into Git comments:
+
+`git stripspace --comment-lines < {{path/to/file}}`