patch 8.0.0766: option test fails with +terminal feature

Problem:    Option test fails with +terminal feature.
Solution:   Fix using the right option when checking the value.

Author: brammool

src/option.c

@@ -7465,7 +7465,7 @@ did_set_string_option(
 
 #ifdef FEAT_TERMINAL
     /* 'termkey' */
-    else if (varp == &curwin->w_p_tms)
+    else if (varp == &curwin->w_p_tk)
     {
 	if (*curwin->w_p_tk != NUL && string_to_key(curwin->w_p_tk, TRUE) == 0)
 	    errmsg = e_invarg;

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    766,
 /**/
     765,
 /**/