Architecture Page: Improve Clarity

Intergrate feedback from @tacurran with previous revisions to architecture page, improving clarity, correcting typos, adding links, and improving formatting.

Signed-off-by: Dominic Serio <dominic@flynn.io>
A bunch of important words got deleted from this paragraph. "distributed key-value store" is important, as is "consistent". "consensus-algorithm-powered" is a mouthful.