Fix quotes = in docstring

Author: zonuexe

Diff for: lisp/php-mode.el

@@ -918,7 +918,7 @@ This is was done due to the problem reported here:
 (defun php-lineup-string-cont (langelem)
   "Line up string toward equal sign or dot.
 e.g.
-$str = 'some'
+$str \= 'some'
      . 'string';
 this ^ lineup"
   (save-excursion