Fix critical discrepancies in v1 API documentation

- Fixed Notes section HTTP methods and endpoints:
  * Get a Specific Note: Corrected from POST /reminders to GET /notes/{note_id}
  * Update a Note: Corrected from POST to PUT /notes/{note_id}
  * Delete a Note: Corrected from PUT to DELETE /notes/{note_id}
  * Fixed all example requests/responses to match correct endpoints

- Fixed heading pluralization to match live site:
  * List Type → List Types
  * Get All Lists Entries → Get All List Entries
  * Field Value Type → Field Value Types
  * Get Field Value → Get Field Values
  * Get All Entity Files → Get All Files
  * Field Value Value Type → Field Value Value Types
  * Field Value Change action type → Field Value Change action types

- Removed extra standalone headings:
  * Removed standalone '#### Webhook' heading under Webhooks H1
  * Removed standalone '#### Reminder' heading under Reminders H1

- Fixed navigation inconsistency:
  * Rate Limit Endpoint → Rate Limit (heading and TOC)

All changes verified against live site at https://api-docs.affinity.co/

Author: yaniv-golan