Typos | incomplete grammar in keypair example documentation

[BHunter2889]

There are some typos/grammatical errors or incomplete sentences in the keypair example docs.

This is the first instance I found:

witness-examples/keypair/README.md

Line 54 in b015940

Now that we have created the keypairs, we can you use to sign attestations we generate.

And the second, which is on the last line (looks to be some errant copy-pasta):

witness-examples/keypair/README.md

Line 197 in b015940

One of the key benefits of using Witness is that it is not only a standalone tool, but also a library that can be embedded into other applications such as admission controllers and runtime visibili