Fix example code for the NERDTreeAddKeyMap function. (#1116)

* Fix example code for the NERDTreeAddKeyMap function.

The quickhelpText didn't match what the statement in the callback
function actually did.

* Update version number in change log.

CHANGELOG.md

@@ -5,7 +5,10 @@
         - **.PATCH**: Pull Request Title (PR Author) [PR Number](Link to PR)
 -->
 #### 6.7
-- **.5**: Prevent unneeded tree creation in :NERDTreeToggle[VCS] <path> (PhilRunninger) [#1101](https://github.com/preservim/nerdtree/pull/1101)
+- **.8**: Fix example code for the NERDTreeAddKeyMap function. (PhilRunninger) [#1116](https://github.com/preservim/nerdtree/pull/1116)
+- **.7**: Put '%' argument in bufname() for backwards compatibility. (PhilRunninger) [#1105](https://github.com/preservim/nerdtree/pull/1105)
+- **.6**: If a file's already open in the window, don't edit it again. (PhilRunninger) [#1103](https://github.com/preservim/nerdtree/pull/1103)
+- **.5**: Prevent unneeded tree creation in `:NERDTreeToggle[VCS] <path>` (PhilRunninger) [#1101](https://github.com/preservim/nerdtree/pull/1101)
 - **.4**: Add missing calls to the `shellescape()` function (lifecrisis) [#1099](https://github.com/preservim/nerdtree/pull/1099)
 - **.3**: Fix vsplit to not open empty buffers when opening previously closed file (AwkwardKore) [#1098](https://github.com/preservim/nerdtree/pull/1098)
 - **.2**: Fix infinity loop (on winvim) in FindParentVCSRoot (Eugenij-W) [#1095](https://github.com/preservim/nerdtree/pull/1095)

doc/NERDTree.txt

@@ -1353,12 +1353,12 @@ NERDTreeAddKeyMap({options})                               *NERDTreeAddKeyMap()*
     Example: >
         call NERDTreeAddKeyMap({
                \ 'key': 'foo',
-               \ 'callback': 'NERDTreeCDHandler',
+               \ 'callback': 'NERDTreeEchoPathHandler',
                \ 'quickhelpText': 'echo full path of current node',
                \ 'scope': 'DirNode' })
 
-        function! NERDTreeCDHandler(dirnode)
+        function! NERDTreeEchoPathHandler(dirnode)
-            call a:dirnode.changeToDir()
+            echo a:dirnode.path.str()
         endfunction
 <
     This code should sit in a file like ~/.vim/nerdtree_plugin/mymapping.vim.

lib/nerdtree/path.vim

@@ -295,7 +295,10 @@ endfunction
 
 " FUNCTION: Path.edit() {{{1
 function! s:Path.edit()
-    exec 'edit ' . self.str({'format': 'Edit'})
+    let l:bufname = self.str({'format': 'Edit'})
+    if bufname('%') !=# l:bufname
+        exec 'edit ' . l:bufname
+    endif
 endfunction
 
 " FUNCTION: Path.extractDriveLetter(fullpath) {{{1