chore(docs): add tracestate and whitespace to spelling list (#5440)

Update the spelling list to include the words `tracestate` and
`whitespace` which are needed for the `build_docs` job to complete
successfully.


https://app.circleci.com/pipelines/github/DataDog/dd-trace-py/31885/workflows/36b716a8-d8dd-420f-b078-6b7a9eaa72c0/jobs/2157818


## Checklist

- [x] Change(s) are motivated and described in the PR description.
- [x] Testing strategy is described if automated tests are not included
in the PR.
- [x] Risk is outlined (performance impact, potential for breakage,
maintainability, etc).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/contributing.html#Release-Note-Guidelines)
are followed.
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/)).
- [x] Author is aware of the performance implications of this PR as
reported in the benchmarks PR comment.

## Reviewer Checklist

- [x] Title is accurate.
- [x] No unnecessary changes are introduced.
- [x] Description motivates each change.
- [x] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [x] Testing strategy adequately addresses listed risk(s).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] Release note makes sense to a user of the library.
- [x] Reviewer is aware of, and discussed the performance implications
of this PR as reported in the benchmarks PR comment.

Author: brettlangdon

docs/spelling_wordlist.txt

@@ -178,6 +178,7 @@ submodule
 submodules
 substring
 timestamp
+tracestate
 tweens
 uWSGI
 unbuffered
@@ -197,6 +198,7 @@ versioned
 vertica
 w3c
 whitelist
+whitespace
 workflow
 wsgi
 xfail