[docs] Document driver mode (#1890)

## Description

Adds documentation for driver mode because it currently isn't
documented.

Closes #1824

## Meta

Merge checklist:
- [x] Pull Request title is [short, imperative
summary](https://cbea.ms/git-commit/) of proposed changes
- [x] The description documents the _what_ and _why_
- [x] If this PR changes behavior or adds a feature, user documentation
is updated
- [x] If this PR touches photon-serde, all messages have been
regenerated and hashes have not changed unexpectedly
- [x] If this PR touches configuration, this is backwards compatible
with settings back to v2024.3.1
- [x] If this PR touches pipeline settings or anything related to data
exchange, the frontend typing is updated
- [x] If this PR addresses a bug, a regression test for it is added

---------

Co-authored-by: Gold856 <117957790+Gold856@users.noreply.github.com>
Co-authored-by: Sam Freund <techguy763@gmail.com>

docs/source/index.md

@@ -102,6 +102,7 @@ docs/pipelines/index
 docs/apriltag-pipelines/index
 docs/reflectiveAndShape/index
 docs/objectDetection/index
+docs/driver-mode/index
 docs/calibration/calibration
 ```