zsh: add watchc function

this allows for watching a process while highlighting its output
with `grc`

functions/misc.zsh

@@ -333,3 +333,8 @@ function watch_file() {
     set -m # restore job control messages
   }
 }
+
+# use watch and force color with grc
+function watchc() {
+	watch --differences --interval 1 --color grc --colour=on $@
+}