documentation update

[avinashatgit]

It would be good to update readme doc with following information

A) After flash installation ensure that you project's manifest.json file contains flash in the Plugins list.
Something like :
{
"Language": "java",
"Plugins": [
"html-report",
"flash"
]
}

B) Where it find the flash report url

• you can execute the specs using gauge run specs and open the URL shown in console output in browser.

C) How to make url static

• Using FLASH_SERVER_PORT in flash.properties file

[zabil]

@avinashatgit Please feel free to open a pull request with the proposed changes!

[nehashri]

@avinashatgit Please feel free to open a Pull Request with the changes suggested. Thanks.