fix: legacy pricing occurrences (#252)

* fix legacy pricing occurrences

* fix growth plan

* pro -> Pro

---------

Co-authored-by: flo merian <[email protected]>
Co-authored-by: Ronan McCarter <[email protected]>

Author: 3 people

advanced/custom/css.mdx

@@ -4,7 +4,7 @@ description: 'Fully customize your documentation with custom CSS'
 ---
 
 <Check>
-  Custom CSS is available as an add-on to the [pro plan](https://mintlify.com/pricing).
+  Custom CSS is available as an add-on to the [Pro plan](https://mintlify.com/pricing).
 </Check>
 
 Add any number of CSS files to your repository and the defined class names will be applied and available across all of your MDX files.

advanced/custom/js.mdx

@@ -4,7 +4,7 @@ description: 'Add JavaScript functionality globally'
 ---
 
 <Check>
-  Custom JS is available as an add-on to the [pro plan](https://mintlify.com/pricing).
+  Custom JS is available as an add-on to the [Pro plan](https://mintlify.com/pricing).
 </Check>
 
 Custom JS allows you to add custom executable code globally. It is the equivalent of adding a `<script>` tag with JS code into every page.

advanced/rest-api/overview.mdx

@@ -3,7 +3,7 @@ title: Introduction
 ---
 
 <Check>
-  The Mintlify REST API is only available on the startup plan and above.
+  The Mintlify REST API is only available on the [Pro plan and above](https://mintlify.com/pricing).
 </Check>
 
 Leverage the external API to programmatically trigger an update when desired.