Add tendermint client docs

[colin-axner]

Summary

Add documentation for the tendermint client under a "light clients" section which includes docs for tendermint and solo machine.

One thing in particular I'd like to add is documentation on how to use the optional migration function PruneAllExpiredConsensusStates

---

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged/assigned

[crodriguezvega]

Work has been started with #6801. Will continue later on.