patch 7.4.1806

Problem:    'termguicolors' option missing from the options window.
Solution:   Add the entry.

src/version.c

@@ -753,6 +753,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1806,
 /**/
     1805,
 /**/