docs: improve cloudflare provider page

[ymansurozer]

🔗 Linked issue

Resolves #1546 and #805.

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

The documentation for Cloudflare is missing an important step, which is to enable image transformations for the deployment URL at Cloudflare dashboard. Otherwise, the module does not work and it causes a lot of confusion for initial setup. This PR aims to clarify this with a warning callout.

[danielroe]

Thank you!

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 62.98%. Comparing base (e7e670d) to head (8aa5eaa).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1601   +/-   ##
=======================================
  Coverage   62.98%   62.98%           
=======================================
  Files          79       79           
  Lines        3534     3534           
  Branches      406      407    +1     
=======================================
  Hits         2226     2226           
  Misses       1279     1279           
  Partials       29       29           

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