message: chore(docs): remove reference to deprecated integration
  Remove reference to deprecated integration `bitbucket` at `index.md`.
diff: @@ -16,17 +16,13 @@ integrations are used by many Backstage core features and other plugins.
  Each key under `integrations` is a separate configuration for a single external
  provider. Providers each have different configuration; here's an example of
  -configuration to use both GitHub and Bitbucket:
  +configuration to use GitHub:
  ```yaml
  integrations:
  github:
  - host: github.com
  token: ${GITHUB_TOKEN}
  - bitbucket:
  - - host: bitbucket.org
  - username: ${BITBUCKET_USERNAME}
  - appPassword: ${BITBUCKET_APP_PASSWORD}
  ```
  See documentation for each type of integration for full details on
  