docs: update workato docs

[daveomri]

Summary

• Simplify the Workato authentication section by removing the OAuth 2.0 flow and keeping only API token authentication. The two methods were split into separate subsections before; now it's a single streamlined set of steps.
• Add a lead paragraph and horizontal rule at the top of the page for consistency with other integration pages.
• Update connector details to reflect current behavior: crawler type list (removed JSDOM), memory range info, validation rules for URL fields and dataset item limits, Actor name format (owner/name with slash and tilde).
• Remove promotional/filler language ("Perfect for real-time data extraction triggered by recipes") and fix minor formatting issues (curly quotes, trailing whitespace).
• Update the Discord link text to "developer community on Discord" and replace the removed OAuth troubleshooting tip with a validation errors tip.

Follow-up TODOs

• Delete unused OAuth screenshots - Two images on disk are no longer referenced in the doc:
  • sources/platform/integrations/images/workato/create-connection-oauth.png
  • sources/platform/integrations/images/workato/create-connection-oauth-success.png
• Delete orphaned create-connection.png - This image exists on disk but is not referenced anywhere in the doc (neither before nor after the changes).
• Update create-connection-api-key.png - This screenshot likely shows the old authentication dialog with the auth type dropdown (API token vs OAuth). Since OAuth was removed, the screenshot should be retaken to show the simplified dialog with only the API token field.
• Update create-connection-api-success.png - Same reason; verify it doesn't show traces of the old OAuth option.
• Update create-connection-find-connector.png and connection-selection.png - Verify these screenshots still match the current Workato UI. If the connector search or selection screen changed, retake them.
• Review remaining screenshots against the live Workato UI. Since the connector was updated (new validation, removed JSDOM crawler, etc.), some action screenshots (run-actor.png, run-task.png, scrape-url.png) may show outdated fields or options.