Update the Readme

[sparrowDom]

The "Deploy stable-ng plain pool" section of the Readme can be misleading. When configuring the Oracle function selector for an Oracle-type asset in the pool:

• one must pass the function name along with parentheses
• Just passing the already computed (using keccak) function selector doesn't work. Allowing the 0x00000000 as the zero method name might imply otherwise. It can be additionally confusing as the pools themselves are created using the keccak-ed selectors and not function names. example