Add documentation.inner / documentation.outer as text objects

Is your feature request related to a problem? Please describe.
I'd like to be able to use did and dad to delete the inner and outer docstring of various languages.

Now that treesitter supports documentation capture groups it'd be great if nvim-treesitter-textobjects could follow suit.

Describe the solution you'd like
I have a fork of this repo where I've implemented one for Python. I can contribute that as a PR, if you're up for it.

Describe alternatives you've considered
None.

Additional context
Here's a GIF showing the fork I've been using so far. Seems to be working.

dad

did

Using configuration

                    select = {
                        enable = true,

                        -- Automatically jump forward to textobj, similar to targets.vim
                        lookahead = true,

                        -- ...

                        keymaps = {
                            ["ad"] = {
                                desc = "Select around an entire docstring",
                                query = "@documentation.outer",
                            },
                            ["id"] = {
                                desc = "Select the inside of a docstring",
                                query = "@documentation.inner",
                            },

                        -- ...

No repository file or test is named. Start with the select.keymaps configuration in the issue and compare the fork's Python implementation with Tree-sitter's documentation capture groups. Done means did and dad can select the inner and outer docstring through @documentation.inner and @documentation.outer for the intended languages.