add: local testing modifier opts in readme

Author: Ankit098

README.md

@@ -40,7 +40,7 @@ export.config = {
 In order to authorize to the BrowserStack service your config needs to contain a [`user`](https://webdriver.io/docs/options#user) and [`key`](https://webdriver.io/docs/options#key) option.
 
 ### browserstackLocal
-Set this to true to enable routing connections from Browserstack cloud through your computer. You will also need to set `browserstack.local` to true in browser capabilities.
+Set this to true to enable routing connections from Browserstack cloud through your computer. 
 
 Type: `Boolean`<br />
 Default: `false`
@@ -52,11 +52,96 @@ Type: `Boolean`<br />
 Default: `false`
 
 ### opts
-Specified optional will be passed down to BrowserstackLocal. See [this list](https://www.browserstack.com/local-testing#modifiers) for details.
+Specified optional will be passed down to BrowserstackLocal. 
 
 Type: `Object`<br />
 Default: `{}`
 
+List of available local testing modifiers to be passed as opts:
+#### Local Identifier
+If doing simultaneous multiple local testing connections, set this uniquely for different processes -
+```js
+opts = { 'localIdentifier': 'randomstring' }
+```
+#### Verbose Logging
+To enable verbose logging -
+```js
+opts = { 'verbose': 'true' }
+```
+Note - Possible values for 'verbose' modifier are '1', '2', '3' and 'true'
+
+#### Folder Testing
+To test local folder rather internal server, provide path to folder as value of this option -
+```js
+opts = { 'f': '/my/awesome/folder' }
+```
+
+#### Force Start
+To kill other running Browserstack Local instances -
+```js
+opts = { 'force': 'true' }
+```
+
+#### Only Automate
+To disable local testing for Live and Screenshots, and enable only Automate -
+```js
+opts = { 'onlyAutomate': 'true' }
+```
+
+#### Force Local
+To route all traffic via local(your) machine -
+```js
+opts = { 'forceLocal': 'true' }
+```
+
+#### Proxy
+To use a proxy for local testing -
+
+* proxyHost: Hostname/IP of proxy, remaining proxy options are ignored if this option is absent
+* proxyPort: Port for the proxy, defaults to 3128 when -proxyHost is used
+* proxyUser: Username for connecting to proxy (Basic Auth Only)
+* proxyPass: Password for USERNAME, will be ignored if USERNAME is empty or not specified
+
+```js
+opts = { 'proxyHost': '127.0.0.1', 'proxyPort': '8000', 'proxyUser': 'user', 'proxyPass': 'password' }
+```
+
+#### Local Proxy
+To use local proxy in local testing -
+
+* localProxyHost: Hostname/IP of proxy, remaining proxy options are ignored if this option is absent
+* localProxyPort: Port for the proxy, defaults to 8081 when -localProxyHost is used
+* localProxyUser: Username for connecting to proxy (Basic Auth Only)
+* localProxyPass: Password for USERNAME, will be ignored if USERNAME is empty or not specified
+
+```js
+opts = { 'localProxyHost': '127.0.0.1', 'localProxyPort': '8000', 'localProxyUser': 'user', 'localProxyPass': 'password' }
+```
+
+#### PAC (Proxy Auto-Configuration)
+To use PAC (Proxy Auto-Configuration) in local testing -
+
+* pac-file: PAC (Proxy Auto-Configuration) file’s absolute path
+
+```js
+opts = { 'pac-file': '<pac_file_abs_path>' }
+```
+
+#### Binary Path
+ 
+ By default, BrowserStack local wrappers try downloading and executing the latest version of BrowserStack binary in ~/.browserstack or the present working directory or the tmp folder by order. But you can override these by passing the -binarypath argument.
+ Path to specify local Binary path -
+ ```js
+ opts = { 'binarypath': '/browserstack/BrowserStackLocal' }
+ ```
+
+#### Logfile
+To save the logs to the file while running with the '-v' argument, you can specify the path of the file. By default the logs are saved in the local.log file in the present woring directory.
+To specify the path to file where the logs will be saved -
+```js
+opts = { 'verbose': 'true', 'logFile': '/browserstack/logs.txt' }
+```
+
 ----
 
 For more information on WebdriverIO see the [homepage](https://webdriver.io).