Formatting Issues in Webhooks Documentation

[RobertKeyser]

Purpose

Update webhooks docs to fix minor formatting issues. https://ethyca.github.io/fidesops/guides/policy_webhooks/

Example: The following screenshot does not render the path parameter:

Changes

• changed typo in docs from derived)identity to derived_identity
• replaced <> with {} for code sample titles

Checklist

• Update CHANGELOG.md file
  • Merge in main so the most recent CHANGELOG.md file is being appended to
  • Add description within the Unreleased section in an appropriate category. Add a new category from the list at the top of the file if the needed one isn't already there.
  • Add a link to this PR at the end of the description with the PR number as the text. example: #1
• Applicable documentation updated (guides, quickstart, postman collections, tutorial, fidesdemo, database diagram.
• If docs updated (select one):
  • documentation complete, or draft/outline provided (tag docs-team to complete/review on this branch)
  • documentation issue created (tag docs-team to complete issue separately)
• Good unit test/integration test coverage
• This PR contains a DB migration. If checked, the reviewer should confirm with the author that the down_revision correctly references the previous migration before merging
• The Run Unsafe PR Checks label has been applied, and checks have passed, if this PR touches any external services