Update usage.md

[imarovec28]

import { web3Accounts, web3Enable, web3FromAddress, web3ListRpcProviders, web3UseRpcProvider } from '@polkadot/extension-dapp';

// returns an array of all the injected sources // (this needs to be called first, before other requests) const allInjected = await web3Enable('my cool dapp');

// returns an array of { address, meta: { name, source } } // meta.source contains the name of the extension that provides this account const allAccounts = await web3Accounts();

// the address we use to use for signing, as injected const SENDER = '5DTestUPts3kjeXSTMyerHihn1uwMfLj8vU8sqF7qYrFabHE';

// finds an injector for an address const injector = await web3FromAddress(SENDER);

// sign and send our transaction - notice here that the address of the account // (as retrieved injected) is passed through as the param to the signAndSend, // the API then calls the extension to present to the user and get it signed. // Once complete, the api sends the tx + signature via the normal process api.tx.balances .transfer('5C5555yEXUcmEJ5kkcCMvdZjUo7NGJiQJMS7vZXEeoMhj3VQ', 123456) .signAndSend(SENDER, { signer: injector.signer }, (status) => { ... });