patch 8.2.1401: cannot jump to the last used tabpage

Problem:    Cannot jump to the last used tabpage.
Solution:   Add g<Tab> and tabpagnr('#'). (Yegappan Lakshmanan, closes #6661,
            neovim #11626)

runtime/doc/eval.txt

@@ -10357,8 +10357,13 @@ tabpagebuflist([{arg}])					*tabpagebuflist()*
 tabpagenr([{arg}])					*tabpagenr()*
 		The result is a Number, which is the number of the current
 		tab page.  The first tab page has number 1.
-		When the optional argument is "$", the number of the last tab
-		page is returned (the tab page count).
+
+		The optional argument {arg} supports the following values:
+			$	the number of the last tab page (the tab page
+				count).
+			#	the number of the last accessed tab page
+				(where |g<Tab>| goes to). if there is no
+				previous tab page 0 is returned.
 		The number can be used with the |:tab| command.
 
 

runtime/doc/index.txt

@@ -440,6 +440,7 @@ tag		char	      note action in Normal mode	~
 |<C-LeftMouse>|	<C-LeftMouse>	   ":ta" to the keyword at the mouse click
 |<C-Right>|	<C-Right>	1  same as "w"
 |<C-RightMouse>| <C-RightMouse>	   same as "CTRL-T"
+|<C-Tab>|	<C-Tab>		   same as "g<Tab>"
 |<Del>|		["x]<Del>	2  same as "x"
 |N<Del>|	{count}<Del>	   remove the last digit from {count}
 |<Down>|	<Down>		1  same as "j"
@@ -587,6 +588,8 @@ tag		command		   action in Normal mode	~
 				   following the file name.
 |CTRL-W_gt|	CTRL-W g t	   same as `gt`: go to next tab page
 |CTRL-W_gT|	CTRL-W g T	   same as `gT`: go to previous tab page
+|CTRL-W_g<Tab>|	CTRL-W g <Tab>	   same as |g<Tab>|: go to last accessed tab
+				   page.
 |CTRL-W_h|	CTRL-W h	   go to Nth left window (stop at first window)
 |CTRL-W_i|	CTRL-W i	   split window and jump to declaration of
 				   identifier under the cursor
@@ -805,6 +808,7 @@ tag		char	      note action in Normal mode	~
 |g<LeftMouse>|	g<LeftMouse>	   same as <C-LeftMouse>
 		g<MiddleMouse>	   same as <C-MiddleMouse>
 |g<RightMouse>|	g<RightMouse>	   same as <C-RightMouse>
+|g<Tab>|	g<Tab>		   go to the last accessed tab page.
 |g<Up>|		g<Up>		1  same as "gk"
 
 ==============================================================================

runtime/doc/tabpage.txt

@@ -221,6 +221,8 @@ gT		Go to the previous tab page.  Wraps around from the first one
 							*:tabl* *:tablast*
 :tabl[ast]	Go to the last tab page.
 
+					    *g<Tab>* *CTRL-W_g<Tab>* *<C-Tab>*
+g<Tab>		Go to the last accessed tab page.
 
 Other commands:
 							*:tabs*