Add API documentation

web3.js/src/account.js

@@ -4,13 +4,26 @@ import bs58 from 'bs58';
 import type {KeyPair} from 'tweetnacl';
 
 /**
+ * Base 58 encoded public key
+ *
  * @typedef {string} PublicKey
  */
 export type PublicKey = string;
 
+/**
+ * Represents an account key pair (public and secret keys).
+ */
 export class Account {
   _keypair: KeyPair;
 
+  /**
+   * Create a new Account object
+   *
+   * If the secretKey parameter is not provided a new key pair is randomly
+   * created for the account
+   *
+   * @param secretKey Secret key for the account
+   */
   constructor(secretKey: ?Buffer = null) {
     if (secretKey) {
       this._keypair = nacl.sign.keyPair.fromSecretKey(secretKey);
@@ -19,10 +32,16 @@ export class Account {
     }
   }
 
+  /**
+   * The public key for this account
+   */
   get publicKey(): PublicKey {
     return bs58.encode(this._keypair.publicKey);
   }
 
+  /**
+   * The **unencrypted** secret key for this account
+   */
   get secretKey(): Buffer {
     return this._keypair.secretKey;
   }