patch 9.0.0828: various typos

Problem:    Various typos.
Solution:   Correct typos. (closes #11432)
diff --git a/src/terminal.c b/src/terminal.c
index 1da9d2d..816ab81 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -2396,7 +2396,7 @@
 }
 
 /*
- * Return the highight group ID for the terminal and the window.
+ * Return the highlight group ID for the terminal and the window.
  */
     static int
 term_get_highlight_id(term_T *term, win_T *wp)