Fix: docs: typos and minor fixes

### Implementation

Consider to plit architecture into implementors, and don't rely on specific choices:

Consider to split architecture into implementations, and don't rely on specific choices:

* Onion Services:

    * Arti is an implementor for the Onion Service protocol.

    * Arti is an implementation for the Onion Service protocol.

    * Consider also to support C Tor as another Onion Service implementation.

      Involves more work, but may be useful for operators that want to migrate

      from solutions such as [Onionspray][] while Arti does not have Onion

```

Not sticking with an specific tool allows Oniongroove to be sustainable in the

long term if the uderlying deployment technology changes or if the community

long term if the underlying deployment technology changes or if the community

prefers to change implementations.

### Modularization