Added some description on how Amber works

Proposed change

All I did was I added some info to the Amber electric page. I am currently in the process of implementing selling electricity to Amber via HA in my setup. Once I have finished, I will add a tutorial onto the page.

Type of change

• Spelling, grammar or other readability improvements (current branch).
• [x ] Adjusted missing or incorrect information in the current documentation (current branch).
• Added documentation for a new integration I'm adding to Home Assistant (next branch).
  • I've opened up a PR to add logos and icons inBrands repository.
• Added documentation for a new feature I'm adding to Home Assistant (next branch).
• Removed stale or deprecated documentation.

Additional information

• Link to parent pull request in the codebase: N/A
• Link to parent pull request in the Brands repository: N/A
• This PR fixes or closes issue: fixes # N/A

Checklist

• This PR uses the correct branch, based on one of the following:
  • I made a change to the existing documentation and used thecurrent branch.
  • I made a change that is related to an upcoming version of Home Assistant and used thenext branch.
• The documentation follows the Home Assistant documentationstandards.