Build the "TeSS Platform in use" section like "FAIRDOM In Use" #1

The TeSS Platform is used by several communities across the globe, as described here https://github.com/ElixirTeSS/docs/blob/main/TeSS_docs/overview/global.md

Some of these instances are considered hubs:

• ELIXIR TeSS / ELIXIR TeSSHub
• PaN-Training / Helmholtz TeSS
• TeSSHub4EOSC

The FAIRDOM Consortium has a feature where instances of its FAIRDOM-SEEK software in use are described https://github.com/FAIRdom/fairdom.github.io/tree/master/pages/fairdom_in_use

This repo "ELIXIRTess/platform is built in a similar way to FAIRDOM.

Recreate the FAIRDOM In Use feature in this repo, with a page type for TeSS Platform and another page type for TeSSHubs.
Create a page for each TeSS instance: ELIXIR TeSS, PaN Training, SciLifeLab, Taxila, HEP Training, EVERSE Training, DReSA, Explora.
Update the "in_use" page to include the website sections feature like on https://github.com/FAIRdom/fairdom.github.io/blob/master/pages/fairdom_in_use/fdom_in_use.md
Create a new "tesshubs" page like https://github.com/FAIRdom/fairdom.github.io/blob/master/pages/fairdom_in_use/fairdom-seek-hubs.md
Create a new "tess-platforms" https://github.com/FAIRdom/fairdom.github.io/blob/master/pages/fairdom_in_use/fairdom-seek-projects.md