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/buffer.c b/src/buffer.c
index 15fbc17..d190bdf 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -4951,7 +4951,7 @@
  * When resolving a link both "*sfname" and "*ffname" will point to the same
  * allocated memory.
  * The "*ffname" and "*sfname" pointer values on call will not be freed.
- * Note that the resulting "*ffname" pointer should be considered not allocaed.
+ * Note that the resulting "*ffname" pointer should be considered not allocated.
  */
     void
 fname_expand(