Migrate the infrastructure library to a separate project

Why is this change being made?

Infrastructure blueprints and designs are stored in the set of pages in the library handbook. This is useful at the moment we want to present the details of any work we do, but the page gets immediately outdated as soon as the work gets started on it.

This causes the following problems:

1. People searching the handbook find outdated information, and reference no longer correct state.
2. Customers find details that are misleading, because both blueprints and designs are only a snapshot in time, rather than showing the current state.
3. Information in this document reaches the Infrastructure department, and we need to explain why the handbook page is incorrect.
4. Library files get updated very rarely.

For this reason, move the library files to the readiness project, with gitlab-com/gl-infra/readiness!37 (merged) .

The benefit is that his project already contains the readiness reviews for larger items we are placing in production, which closes the full loop:

1. Blueprint is the general idea we want to put in place.
2. Design is the proposal on how we want to implement it.
3. Readiness review is how we implemented it.

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
• 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.
  • 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.

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