WIP: Deep Dive on each Purchase Request Type with Negotiation Guidelines

Creating a specific page for a detailed deep dive on the purchase request process for each purchase type. This will provide clarity to the user by only presenting the information they need for creating their issue, rather than having it combined with other issue types (ie marketing, hotels, consultants, etc)

Why is this change being made?

Adding detailed content on the reasons for each intake field to encourage completion and avoid delays in review and approvals.

Author Checklist

• Provided a concise title for the MR
• Added a description to this MR explaining the reasons for the proposed change, per [say-why-not-just-what][transparency]
• Assign this change to the correct DRI
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to your manager.
  • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in [#mr-buddies][mr-buddies-slack].
  • If the changes relate to any part of the project other than updates to content and/or data files please make sure to ping @gl-static-site-editor in a comment for a review and merge. For example changes to .gitlab-ci.yml, JavaScript/CSS/Ruby code or the layout files.