runtime(doc): buffers can be re-used

while at it, also move the note about :wincmd
directly to :h :wincmd, it doesn't seem to belong to the buffer section.

closes: #15636

Signed-off-by: Christian Brabandt <[email protected]>

Author: chrisbra

runtime/doc/tags

@@ -6192,6 +6192,7 @@ bufexists()	builtin.txt	/*bufexists()*
 buffer-functions	usr_41.txt	/*buffer-functions*
 buffer-hidden	windows.txt	/*buffer-hidden*
 buffer-list	windows.txt	/*buffer-list*
+buffer-reuse	windows.txt	/*buffer-reuse*
 buffer-variable	eval.txt	/*buffer-variable*
 buffer-write	editing.txt	/*buffer-write*
 buffer_exists()	builtin.txt	/*buffer_exists()*

runtime/doc/windows.txt

@@ -1,4 +1,4 @@
-*windows.txt*   For Vim version 9.1.  Last change: 2024 Jul 09
+*windows.txt*   For Vim version 9.1.  Last change: 2024 Sep 07
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -67,11 +67,17 @@ active		  yes		 yes		  'a'
 hidden		  no		 yes		  'h'
 inactive	  no		 no		  ' '
 
-Note: All CTRL-W commands can also be executed with |:wincmd|, for those
-places where a Normal mode command can't be used or is inconvenient.
+							*buffer-reuse*
+Each buffer has a unique number and the number will not change within a Vim
+session.  The |bufnr()| and |bufname()| functions can be used to convert
+between a buffer name and the buffer number.  There is one exception: if a new
+empty buffer is created and it is not modified, the buffer will be re-used
+when loading another file into that buffer. This also means the buffer number
+will not change.
 
 The main Vim window can hold several split windows.  There are also tab pages
 |tab-page|, each of which can hold multiple windows.
+
 					*window-ID* *winid* *windowid*
 Each window has a unique identifier called the window ID.  This identifier
 will not change within a Vim session. The |win_getid()| and |win_id2tabwin()|
@@ -83,9 +89,6 @@ across tabs.  For most functions that take a window ID or a window number, the
 window number only applies to the current tab, while the window ID can refer
 to a window in any tab.
 
-Each buffer has a unique number and the number will not change within a Vim
-session.  The |bufnr()| and |bufname()| functions can be used to convert
-between a buffer name and the buffer number.
 
 ==============================================================================
 2. Starting Vim						*windows-starting*
@@ -485,6 +488,10 @@ These commands can also be executed with ":wincmd":
 			:exe nr .. "wincmd w"
 <		This goes to window "nr".
 
+Note: All CTRL-W commands can also be executed with |:wincmd|, for those
+places where a Normal mode command can't be used or is inconvenient (e.g.
+in a browser-based terminal).
+
 ==============================================================================
 5. Moving windows around				*window-moving*