Remove mentions of old farmerbot

[Mik-TF]

Issue

The old farmerbot docs are still on the manual

Todo

• Remove mentions of old farmerbot
• only keep the docs on how to stop the old farmerbot (so users can set the new version)

[Mik-TF]

e.g. remove all qna on old farmerbot, and add this mention to the current fbot guide.

"if you're still using the old version of the farmerbot, follow those steps to stop this version of the farmerbot, then head to the new farmerbot guide and set the new bot for your farm!"

[Mik-TF]

fixed when #387 is merged.