Spelling corrections plus CI job for codespell

* Use codespell to check spelling in documentation, refs #1417
* Fixed spelling errors spotted by codespell, closes #1417
* Make codespell a docs dependency

See also this TIL:  https://til.simonwillison.net/python/codespell

docs/changelog.rst

@@ -426,7 +426,7 @@ See also `Datasette 0.49: The annotated release notes <https://simonwillison.net
 - Datasette now has `a GitHub discussions forum <https://github.com/simonw/datasette/discussions>`__ for conversations about the project that go beyond just bug reports and issues.
 - Datasette can now be installed on macOS using Homebrew! Run ``brew install simonw/datasette/datasette``. See :ref:`installation_homebrew`. (:issue:`335`)
 - Two new commands: ``datasette install name-of-plugin`` and ``datasette uninstall name-of-plugin``. These are equivalent to ``pip install`` and ``pip uninstall`` but automatically run in the same virtual environment as Datasette, so users don't have to figure out where that virtual environment is - useful for installations created using Homebrew or ``pipx``. See :ref:`plugins_installing`. (:issue:`925`)
-- A new command-line option, ``datasette --get``, accepts a path to a URL within the Datasette instance. It will run that request through Datasette (without starting a web server) and print out the repsonse. See :ref:`getting_started_datasette_get` for an example. (:issue:`926`)
+- A new command-line option, ``datasette --get``, accepts a path to a URL within the Datasette instance. It will run that request through Datasette (without starting a web server) and print out the response. See :ref:`getting_started_datasette_get` for an example. (:issue:`926`)
 
 .. _v0_46:
 
@@ -500,7 +500,7 @@ New plugin hooks
 Smaller changes
 ~~~~~~~~~~~~~~~
 
-- Cascading view permissons - so if a user has ``view-table`` they can view the table page even if they do not have ``view-database`` or ``view-instance``. (:issue:`832`)
+- Cascading view permissions - so if a user has ``view-table`` they can view the table page even if they do not have ``view-database`` or ``view-instance``. (:issue:`832`)
 - CSRF protection no longer applies to ``Authentication: Bearer token`` requests or requests without cookies. (:issue:`835`)
 - ``datasette.add_message()`` now works inside plugins. (:issue:`864`)
 - Workaround for "Too many open files" error in test runs. (:issue:`846`)
@@ -714,7 +714,7 @@ Also in this release:
 * Datasette now has a *pattern portfolio* at ``/-/patterns`` - e.g. https://latest.datasette.io/-/patterns. This is a page that shows every Datasette user interface component in one place, to aid core development and people building custom CSS themes. (:issue:`151`)
 * SQLite `PRAGMA functions <https://www.sqlite.org/pragma.html#pragfunc>`__ such as ``pragma_table_info(tablename)`` are now allowed in Datasette SQL queries. (:issue:`761`)
 * Datasette pages now consistently return a ``content-type`` of ``text/html; charset=utf-8"``. (:issue:`752`)
-* Datasette now handles an ASGI ``raw_path`` value of ``None``, which should allow compatibilty with the `Mangum <https://github.com/erm/mangum>`__ adapter for running ASGI apps on AWS Lambda. Thanks, Colin Dellow. (`#719 <https://github.com/simonw/datasette/pull/719>`__)
+* Datasette now handles an ASGI ``raw_path`` value of ``None``, which should allow compatibility with the `Mangum <https://github.com/erm/mangum>`__ adapter for running ASGI apps on AWS Lambda. Thanks, Colin Dellow. (`#719 <https://github.com/simonw/datasette/pull/719>`__)
 * Installation documentation now covers how to :ref:`installation_pipx`. (:issue:`756`)
 * Improved the documentation for :ref:`full_text_search`. (:issue:`748`)
 
@@ -1169,7 +1169,7 @@ Documentation improvements plus a fix for publishing to Zeit Now.
 New plugin hooks, improved database view support and an easier way to use more recent versions of SQLite.
 
 - New ``publish_subcommand`` plugin hook. A plugin can now add additional ``datasette publish`` publishers in addition to the default ``now`` and ``heroku``, both of which have been refactored into default plugins. :ref:`publish_subcommand documentation <plugin_hook_publish_subcommand>`. Closes :issue:`349`
-- New ``render_cell`` plugin hook. Plugins can now customize how values are displayed in the HTML tables produced by Datasette's browseable interface. `datasette-json-html <https://github.com/simonw/datasette-json-html>`__ and `datasette-render-images <https://github.com/simonw/datasette-render-images>`__ are two new plugins that use this hook. :ref:`render_cell documentation <plugin_hook_render_cell>`. Closes :issue:`352`
+- New ``render_cell`` plugin hook. Plugins can now customize how values are displayed in the HTML tables produced by Datasette's browsable interface. `datasette-json-html <https://github.com/simonw/datasette-json-html>`__ and `datasette-render-images <https://github.com/simonw/datasette-render-images>`__ are two new plugins that use this hook. :ref:`render_cell documentation <plugin_hook_render_cell>`. Closes :issue:`352`
 - New ``extra_body_script`` plugin hook, enabling plugins to provide additional JavaScript that should be added to the page footer. :ref:`extra_body_script documentation <plugin_hook_extra_body_script>`.
 - ``extra_css_urls`` and ``extra_js_urls`` hooks now take additional optional parameters, allowing them to be more selective about which pages they apply to. :ref:`Documentation <plugin_hook_extra_css_urls>`.
 - You can now use the :ref:`sortable_columns metadata setting <metadata_sortable_columns>` to explicitly enable sort-by-column in the interface for database views, as well as for specific tables.