Adding Wave Gen2 documentation

[precurse]

Description:

Related issue (if applicable): fixes https://github.com/esphome/feature-requests/issues/1795

Pull request in esphome with YAML changes (if applicable):

• esphome/esphome#8460

Checklist:

• [x] I am merging into next because this is new documentation that has a matching pull-request in esphome as linked above.
  or

• [ ] I am merging into current because this is a fix, change and/or adjustment in the current documentation and is not for a new component or feature.

• [ ] Link added in /components/index.rst when creating new documents for new components or cookbook.

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[github-actions[bot]]

There hasn't been any activity on this pull request recently. This pull request has been automatically marked as stale because of that and will be closed if no further activity occurs within 7 days. Thank you for your contributions.

[precurse]

Any idea how long these PRs take to get approved?

[bdraco]

There are a few things missing here:

• What the device_type configuration option does
• Which sensors are/aren't supported on Wave Gen2
• That WAVE_PLUS is the default
• Clear differentiation between the two device types

[precurse]

Ack, I missed this comment! Thanks for the help on this :)