Fundraising tech/notes/Draft:Documentation overhaul

Brainstorming: topics to include

 * FR-Tech source repositories and codebases, what they're used for, where they're deployed, how they're used, links to related documentation pages, links to upstream repos (if applicable)
 * Civicrm: Procedures for updating repos from upstream (civicrm and buildkit)
 * Civicrm: Triggers: What they're for, how to update, how they work for adding fields, how to test, how they're deployed on production and locally
 * Composer: How we run it locally, on production and in CI, and why, and troubleshooting tips
 * Process-control
 * Fundraising tech/Process-control June 2017
 * Deploymet: Steps for all service in the FR stack and config changes
 * Fundraising tech/Deployment August 2021
 * Integrations: Adyen Checkout: Explanation of flow for different payment options (cc, cc with 3DS, rtbt), including pointers to codebases and methods responsible for each step, and UML interaction diagrams
 * It would be nice to have at least just an up to date basic overview of all the integrations with the same topics
 * Or the opposite and have our flow pieces and then describe each of the payment processors
 * DonationInterface: Overview of main classes and methods and their functions in the system
 * LandingCheck extension: where it's installed, how FR systems use it, link to documentation from other FR-Tech documentation.
 * List of public and non-public sites involved in FR systems, and which codebases are installed on each of them, and which servers host them.
 * DonationInterface: Config: Short summary of global config variables and per-processor config mechanism on wiki, with link to README for details; complete doc of all config variables in README, explanation of config in yml files in config folders in source code, explanation of which types of config should go in which locations.
 * Pipeline for selection of country, payment processor, method, recurring, and other variants, from banners or links in e-mails to Payments site.
 * Permissions, use, content layout of wikis: Foundation wiki, Thank you wiki.
 * Acoustic/silverpop export: how it works, how to add fields and backfill, which database export runs (staging?) on and why.
 * Fundraising tech/CiviCRM some documentation is here December 2019
 * Outline of end-to-end donation flows, including code paths
 * Also new, more formal diagram(s) with overview of flows