update the readmes inside this repo to be more useful and include better information about how to use the sdk.

at the very least, the root repo read me and the @solana/actions package readme (they should be mirrored) should be updated with the following:

• clear link to the typedoc docs: https://solana-developers.github.io/solana-actions/
• add the npm installs badge at the top
• example code snippets on the most common functions within this sdk, including (at a minimum):
  • createActionHeaders
  • creating a typed actions.json payload
  • creating a typed get request payload
  • creating a typed post response payload using createPostResponse