json-rpc/docs: fix typos
json-rpc/docs: fix typos

Closes: #7209

libra/libra,libra/libra,aptos-labs/aptos-core,aptos-labs/aptos-core,aptos-labs/aptos-core,aptos-labs/aptos-core,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,libra/libra,libra/libra,aptos-labs/aptos-core