Set commenting options for php

The defaults are working but using c-family style is more idiomatic,
it also enable support for `comment-selection`.

rc/core/commenting.kak

@@ -9,7 +9,7 @@ hook global BufSetOption filetype=asciidoc %{
     set buffer comment_selection_chars '///:///'
 }
 
-hook global BufSetOption filetype=(c|cpp|go|java|javascript|objc|sass|scala|scss|swift) %{
+hook global BufSetOption filetype=(c|cpp|go|java|javascript|objc|php|sass|scala|scss|swift) %{
     set buffer comment_line_chars '//'
     set buffer comment_selection_chars '/*:*/'
 }