etckeeper: add page (#3076)

pages/linux/etckeeper.md

@@ -0,0 +1,24 @@
+# etckeeper
+
+> Track system configuration files in git.
+> More information: <http://etckeeper.branchable.com/>.
+
+- Set up a git repo and perform various setup tasks (run from /etc):
+
+`sudo etckeeper init`
+
+- Commit all changes in /etc:
+
+`sudo etckeeper commit {{message}}`
+
+- Run arbitrary git commands:
+
+`sudo etckeeper vcs {{status}}`
+
+- Check if there are uncommitted changes (only returns an exit code):
+
+`sudo etckeeper unclean`
+
+- Destroy existing repo and stop tracking changes:
+
+`sudo etckeeper uninit`