Update documentation to match the branding

[nejraselimovic]

Summary

We decided to use:

• For V2 -> The Things Network V2 for community deployment, The Things Industries V2 for private deployments
• For V3 -> The Things Stack and only mention that it is the version 3 (V3) somewhere in the beginning

so the whole documentation needs to reflect this decision.

Why do we need this ?

To avoid confusion with branding

Can you do this yourself and submit a Pull Request?

Yes, but can you @benolayinka and @laurensslats please confirm this is correct before I start making changes

[jpmeijers]

As an end user I would want to see the branding on the console match whatever is used in the documentation:

[jpmeijers]

I've seen @laurensslats is starting to use the name "The Things Stack Community" for the instance I as a community member use. Shouldn't that be "The Things Stack Community Edition", because "The Things Stack Community" sounds like you are referring to the people - the people that makes up the community. Whereas "Community Edition" is clear that it is the instance that is meant for the people in the community.

[nejraselimovic]

Closed with #443.