patch 9.0.0756: no autocmd event for changing text in a terminal window

Problem:    No autocmd event for changing text in a terminal window.
Solution:   Add TextChangedT. (Shougo Matsushita, closes #11366)
diff --git a/src/version.c b/src/version.c
index a917dfd..d987d91 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    756,
+/**/
     755,
 /**/
     754,