patch 8.2.3576: some functions are not documented for use with a method

Problem:    Some functions are not documented for use with a method.
Solution:   Add examples.  Fix that sign_unplacelist() only takes one
            argument. (Sean Dewar, closes #9081)
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 0843824..bbea3b1 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -1955,7 +1955,7 @@
 			ret_number_bool,    SIGN_FUNC(f_sign_undefine)},
     {"sign_unplace",	1, 2, FEARG_1,	    arg2_string_dict,
 			ret_number_bool,    SIGN_FUNC(f_sign_unplace)},
-    {"sign_unplacelist", 1, 2, FEARG_1,	    arg1_list_any,
+    {"sign_unplacelist", 1, 1, FEARG_1,	    arg1_list_any,
 			ret_list_number,    SIGN_FUNC(f_sign_unplacelist)},
     {"simplify",	1, 1, FEARG_1,	    arg1_string,
 			ret_string,	    f_simplify},