Document update-config.json and how this is used in Protractor

[cnishina]

closes #169

[benjaminapetersen]

Possible to provide an example of what this file is supposed to look like? Trying to see if I can spoof it when:

[13:41:49] I/testLogger - [chrome #11] PID: 71282
[chrome #11] [13:41:49] E/local - Error code: 135
[chrome #11] [13:41:49] E/local - Error message: No update-config.json found. Run 'webdriver-manager update' to download binaries.
[chrome #11] [13:41:49] E/local - Error: No update-config.json found. Run 'webdriver-manager update' to download binaries.
[chrome #11]     at IError (~/github/my-project/node_modules/protractor/built/exitCodes.js:6:1)
[chrome #11]     at ProtractorError (~/github/my-project/node_modules/protractor/built/exitCodes.js:11:9)
[chrome #11]     at BrowserError (~/github/my-project/node_modules/protractor/built/exitCodes.js:52:9)
[chrome #11]     at Local.addDefaultBinaryLocs_ (~/github/my-project/node_modules/protractor/built/driverProviders/local.js:57:23)
[chrome #11]     at Local.setupDriverEnv (~/github/my-project/node_modules/protractor/built/driverProviders/local.js:98:14)
[chrome #11]     at Local.setupEnv (~/github/my-project/node_modules/protractor/built/driverProviders/driverProvider.js:111:34)
[chrome #11]     at q.then (~/github/my-project/node_modules/protractor/built/runner.js:335:41)
[chrome #11]     at _fulfilled (~/github/my-project/node_modules/protractor/node_modules/q/q.js:834:54)
[chrome #11]     at self.promiseDispatch.done (~/github/my-project/node_modules/protractor/node_modules/q/q.js:863:30)
[chrome #11]     at Promise.promise.promiseDispatch (~/github/my-project/node_modules/protractor/node_modules/q/q.js:796:13)

If I happen to have a selenium-standalone-server jar, I should be able to manually create this file to hook things up if webdriver-manager update is unable to work successfully.

Related to issues #270 & #269 (Rate limit issues due to unauthenticated requests to github prevent a successful run of webdriver-manager update.)

[benjaminapetersen]

Prev comment, this might assist: https://medium.com/@cnishina/webdriver-manager-a-node-module-c33a820f5eb