cleanup method names and update cca examples

Asset (for ATOM):
base: uatom
display: atom
symbol: ATOM

> Symbol is best for user facing and when you need simplicity.
> Base is good for being the only one guaranteed to be unique per chain.
> The word ‘Display’ I would avoid entirely for these functions.
> And Denom is a bit ambiguous, but is the terminology I see being used on-chain.
> Since we’re just starting to see symbol collisions, I guess Id recommend Denom or Symbol, but also allow for chain name just to avoid ambiguity.
> So getPriceByDenom(uatom, cosmoshub) or getPriceByDenom(uatom) would work.
> And getPriceBySymbol(ATOM) would work and getPriceBySymbol(NOM,onomy) would also work, but getPriceBySymbol(NOM) would fail (or return an array or something) due to the two possibilities.

cc @HebeHe1986