Remove mentions of Macros to render Umbraco Forms

[sofietoft]

Description

I've updated the "Render Forms" article by removing the macro section. I've updated the "Themes article" by linking to the "Rendering Forms" article instead of the example using Macros.

Type of suggestion

• [ ] Typo/grammar fix
• [x] Updated outdated content
• [ ] New content
• [ ] Updates related to a new version
• [ ] Other

Product & version (if relevant)

Forms - 14