Further update the WPMS gui installation

[carl-alberto]

Closes #8334

Summary

Had a full separate guide in doing the subfolder setup, GUI + terminus for WPMS

Effect

Adding additional details on the WPMS setup

Remaining Work and Prerequisites

The following changes still need to be completed:

These guides compliments this PR

• Pantheon specific config do not show by default pantheon-mu-plugin#14
• Simplify the wp-config pantheon-mu-plugin#16

Dependencies and Timing

• Other prerequisites that must be completed before merging this PR

Release:

• When ready
• After date: $DATE

---

Post Launch

Do not remove - To be completed by the docs team upon merge:

• Redirect /old-path/ => /new-path/ (if applicable)
• Include/exclude pages ^ respectively within docs search service provider (if applicable)
• For Heroes - add a props post to the discussion board.
• Remove from the project board

[pantheon-decoupled]

⚡ Deployed with Pantheon Decoupled

This build was successfully deployed with Pantheon. You can track the build logs here.

👀 Preview: https://pr-8417-documentation.appa.pantheon.site
🛠️ Manage in Pantheon: https://dashboard.pantheon.io/site/2b30153f-e8b1-4427-b076-6109e704ba5d/overview

[pantheon-decoupled]

⚡ Deployed with Pantheon Decoupled

This build was successfully deployed with Pantheon. You can track the build logs here.

👀 Preview: https://pr-8417-documentation.appa.pantheon.site
🛠️ Manage in Pantheon: https://dashboard.pantheon.io/site/2b30153f-e8b1-4427-b076-6109e704ba5d/overview

[whitneymeredith]

Preview

[wordsmither]

lgtm