patch 8.0.1494: no autocmd triggered in Insert mode with visible popup menu

Problem:    No autocmd triggered in Insert mode with visible popup menu.
Solution:   Add TextChangedP. (Prabir Shrestha, Christian Brabandt,
            closes #2372, closes #1691)
            Fix that the TextChanged autocommands are not always triggered
            when sourcing a script.
diff --git a/runtime/doc/autocmd.txt b/runtime/doc/autocmd.txt
index ede536e..fe67774 100644
--- a/runtime/doc/autocmd.txt
+++ b/runtime/doc/autocmd.txt
@@ -1,4 +1,4 @@
-*autocmd.txt*   For Vim version 8.0.  Last change: 2018 Feb 09
+*autocmd.txt*   For Vim version 8.0.  Last change: 2018 Feb 10
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -332,6 +332,9 @@
 
 |TextChanged|		after a change was made to the text in Normal mode
 |TextChangedI|		after a change was made to the text in Insert mode
+			when popup menu is not visible
+|TextChangedP|		after a change was made to the text in Insert mode
+			when popup menu visible
 |TextYankPost|		after text is yanked or deleted
 
 |ColorScheme|		after loading a color scheme
@@ -976,6 +979,11 @@
 				current buffer in Insert mode.
 				Not triggered when the popup menu is visible.
 				Otherwise the same as TextChanged.
+							*TextChangedP*
+TextChangedP			After a change was made to the text in the
+				current buffer in Insert mode, only when the
+				popup menu is visible.  Otherwise the same as
+				TextChanged.
 							*TextYankPost*
 TextYankPost			After text has been yanked or deleted in the
 				current buffer.  The following values of