Improve Developer Guides layout & code blocks
Created by: bigreddmachine
This PR includes the following:
- Fix issue with daemon-rpc example styling.
- Remove references to deprecated class “cli-code” and replace with code blocks where necessary.
- Add new line between all RPC calls and outputs.
- Use 3-apostrophe code blocks instead of indent for all curl examples for markdown neatness and to enable future syntax highlighting.