[shell completions] Fix markdown syntax in README.md

linux/completion/README.md

@@ -1,7 +1,7 @@
 Bash completion file will be automatically installed with make install
-into /etc/bash_completion.d/
+into `/etc/bash_completion.d/`
 
 To install zsh completion file, either manually copy it to proper directory
 (one directory from $fpath), or run this command:
 
-cp _qupzilla "`echo $fpath | cut -d' ' -f1`/_qupzilla"
+    cp _qupzilla "`echo $fpath | cut -d' ' -f1`/_qupzilla"