feat: convert from mdbook to Grav format

- Rename src/ to pages/
- Add Grav frontmatter to markdown files
- Create numbered folder structure
- Remove mdbook-specific files

Migration from mdbook to Grav CMS.

src/SUMMARY.md

@@ -1,3 +0,0 @@
-# Summary
-
-- [Introduction](./introduction.md)

src/introduction.md

@@ -1,15 +0,0 @@
-# TeamRental.net
-
-## Executive Summary
-
-- Idea is to have a freelance platform that isn’t horrible like upwork/guru etc has become.
-- Would cross/up sell MerchantsOfHope/YDN.
-- Joint venture with DevWranglers (a non TSYS Group company).
-- MSP (for IT consulting ongoing recrurring passive revenue).
-- Dev Agency(for R&D consulting).
-
-## Reduction to practice
-
-- [GIT Organization](https://git.knownelement.com/TeamRental.net)
-- [Discourse Category](https://community.turnsys.com/c/forprofit/teamrental/33)
-- [Redmine Project](https://projects.knownelement.com/projects/teamrental)