patch 8.1.1955: tests contain typos

Problem:    Tests contain typos.
Solution:   Correct the typos. (Dominique Pelle)
diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
index 9dc578e..0979bb4 100644
--- a/src/testdir/test_autocmd.vim
+++ b/src/testdir/test_autocmd.vim
@@ -1091,7 +1091,7 @@
   call assert_equal(g:opt[0], g:opt[1])
 
 
-  " 33: Test autocomands when an option value is converted internally.
+  " 33: Test autocommands when an option value is converted internally.
   noa set backspace=1 " Reset global and local value (without triggering autocmd)
   let g:options=[['backspace', 'indent,eol', 'indent,eol', 'indent,eol', '2', 'global', 'set']]
   set backspace=2