patch 8.2.2160: various typos

Problem:    Various typos.
Solution:   Fix spelling mistakes. (closes #7494)
diff --git a/src/normal.c b/src/normal.c
index 8dca538..1c66412 100644
--- a/src/normal.c
+++ b/src/normal.c
@@ -5372,7 +5372,7 @@
 nv_subst(cmdarg_T *cap)
 {
 #ifdef FEAT_TERMINAL
-    // When showing output of term_dumpdiff() swap the top and botom.
+    // When showing output of term_dumpdiff() swap the top and bottom.
     if (term_swap_diff() == OK)
 	return;
 #endif