Add codespell support (CI to check, not to fix) and make it fix a few typos (#10297)

Another token of gratitude for a super useful tool and service.

More about codespell: https://github.com/codespell-project/codespell .

I personally introduced it to dozens if not hundreds of projects already
and so far only positive feedback.

CI workflow has 'permissions' set only to 'read' so also should be safe.

---------

Signed-off-by: Yaroslav O. Halchenko <debian@onerussian.com>

certbot/docs/cli-help.txt

@@ -263,7 +263,7 @@ testing:
   --debug               Show tracebacks in case of errors (default: False)
   --no-verify-ssl       Disable verification of the ACME server's certificate.
                         The root certificates trusted by Certbot can be
-                        overriden by setting the REQUESTS_CA_BUNDLE
+                        overridden by setting the REQUESTS_CA_BUNDLE
                         environment variable. (default: False)
   --http-01-port HTTP01_PORT
                         Port used in the http-01 challenge. This only affects

certbot/docs/using.rst

@@ -860,7 +860,7 @@ whether your system has a pre-installed scheduled task for Certbot, it is safe t
 instructions to create one.
 
 .. note::
-   If you're using Windows, these instructions are not neccessary as Certbot on Windows comes with
+   If you're using Windows, these instructions are not necessary as Certbot on Windows comes with
    a scheduled task for automated renewal pre-installed.
 
    If you are using macOS and installed Certbot using Homebrew, follow the instructions at