Update Third Party Hardware landing page and deprecate MyoWare/ThinkPulse guides

[catamgalvan]

The Third Party Hardware landing page (https://docs.openbci.com/ThirdParty/ThirdPartyLanding/) currently lists MyoWare and ThinkPulse Active Electrodes, which are no longer sold.

Remove both from the landing page and add a card for the cEEGrid Kit instead (it's already referenced in the sidebar navigation but missing from this page).

Also deprecate the following pages, since they document discontinued hardware:

• https://docs.openbci.com/ThirdParty/Myoware/MyoWareCyton/
• https://docs.openbci.com/ThirdParty/ThinkPulse/ThinkPulse/