Update doorbird.markdown

[rosscullen]

Proposed change

Type of change

• [x] 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 logo's and icons in Brands repository.
• [ ] Added documentation for a new feature I'm adding to Home Assistant (next branch).
• [ ] Removed stale or deprecated documentation.

Additional information

Additional tweaks to make easier to understand. Automation examples. Addition of Doorbird Web Portal use for easier configuration.

Checklist

• [x] This PR uses the correct branch, based on one of the following:
  • I made a change to the existing documentation and used the current branch.
  • I made a change that is related to an upcoming version of Home Assistant and used the next branch.
• [x] The documentation follows the Home Assistant documentation standards.