patch 8.1.2243: typos in comments

Problem:    Typos in comments.
Solution:   Fix the typos. (Dominique Pelle, closes #5160)  Also adjust
            formatting a bit.
diff --git a/src/autocmd.c b/src/autocmd.c
index 6ed2971..7e8a692 100644
--- a/src/autocmd.c
+++ b/src/autocmd.c
@@ -1584,8 +1584,8 @@
 	    curbuf = curwin->w_buffer;
 	    if (win_valid(aco->save_prevwin))
 		prevwin = aco->save_prevwin;
-	    // In case the autocommand move the cursor to a position that that
-	    // not exist in curbuf.
+	    // In case the autocommand moves the cursor to a position that
+	    // does not exist in curbuf.
 	    check_cursor();
 	}
     }