patch 8.2.0532: cannot use simplify() as a method

Problem:    Cannot use simplify() as a method.
Solution:   Add FEARG_1. (closes #5996)

runtime/doc/eval.txt

@@ -9024,6 +9024,8 @@ simplify({filename})					*simplify()*
 		directory.  In order to resolve all the involved symbolic
 		links before simplifying the path name, use |resolve()|.
 
+		Can also be used as a |method|: >
+			GetName()->simplify()
 
 sin({expr})						*sin()*
 		Return the sine of {expr}, measured in radians, as a |Float|.