patch 8.0.0836: can abandon a terminal buffer after making a change

Problem:    When a terminal buffer is changed it can still be accidentally
            abandoned.
Solution:   When making a change reset the 'buftype' option.
diff --git a/src/version.c b/src/version.c
index 88d7e76..3aab4d3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    836,
+/**/
     835,
 /**/
     834,