Add files completion to _swaylock

completions/zsh/_swaylock

@@ -6,6 +6,6 @@
 _arguments -s \
     '(-v --version)'{-v,--version}'[Show the version number and quit]' \
     '(-h --help)'{-h,--help}'[Show help message and quit]' \
-    '(-c --color)'{-c --color}'[Specify a color (rrggbb) instead of white]' \
+    '(-c --color)'{-c,--color}'[Specify a color (rrggbb) instead of white]:files:_files' \
-    '(-i --image)'{-i --image}'[Display an image]' \
+    '(-i --image)'{-i,--image}'[Display an image]' \
-    '(-s --scaling)'{-s --scaling}'[Scaling mode: stretch, fill, fit, center, tile]'
+    '(-s --scaling)'{-s,--scaling}'[Scaling mode: stretch, fill, fit, center, tile]'