Add key binding to generate docstring

* Add key binding to generate docstring to lang/python layer
* Update documentation

autoload/SpaceVim/layers/lang/python.vim

@@ -80,6 +80,16 @@ function! s:language_specified_mappings() abort
   call SpaceVim#mapping#space#langSPC('nmap', ['l','s', 's'],
         \ 'call SpaceVim#plugins#repl#send("selection")',
         \ 'send selection and keep code buffer focused', 1)
+
+  " +Generate {{{
+
+  let g:_spacevim_mappings_space.l.g = {'name' : '+Generate'}
+
+  call SpaceVim#mapping#space#langSPC('nnoremap', ['l', 'g', 'd'],
+        \ 'Pydocstring', 'generate docstring', 1)
+
+  " }}}
+
   if SpaceVim#layers#lsp#check_filetype('python')
     nnoremap <silent><buffer> K :call SpaceVim#lsp#show_doc()<CR>
 

docs/layers/lang/python.md

@@ -15,6 +15,7 @@ description: "This layer is for Python development, provide autocompletion, synt
   - [Buffer formatting](#buffer-formatting)
   - [Format imports](#format-imports)
 - [Key bindings](#key-bindings)
+  - [Code generation](#code-generation)
   - [Inferior REPL process](#inferior-repl-process)
   - [Running current script](#running-current-script)
   - [Testing](#testing)
@@ -69,6 +70,12 @@ pip install --user isort
 
 ## Key bindings
 
+### Code generation
+
+| Mode   | Key Binding | Description                           |
+| ------ | ----------- | ------------------------------------- |
+| normal | `SPC l g d` | Generate docstring                    |
+
 ### Inferior REPL process
 
 Start a Python or iPython inferior REPL process with `SPC l s i`. If `ipython` is available in system executable search paths, `ipython` will be used to launch python shell; otherwise, default `python` interpreter will be used. You may change your system executable search path by activating a virtual environment.