395cef7 Change getmininginfo errors field to warnings (Andrew Chow)
8502b20 Unify help text for GetWarnings output in get*info RPCs (Andrew Chow)
f77f0e4 Add warnings field to getblockchaininfo (Andrew Chow)
Pull request description:
The `getblockchaininfo` output does not contain the `warnings` field which the `getinfo`, `getmininginfo`, and `getnetworkinfo` RPCs have. It should have it as the errors pertain to the blockchain. This PR adds that field. This PR also unifies the help text for the `warnings` field and its output position so that all of the `get*info` commands are consistent. `getnetworkinfo`'s `errors` field is named `warnings`. I did not change this even though it is inconsistent since this naming has been in use for a long time.