docs: updated proxyConfig property folder path

package.json and proxy.conf.json are now located in the root folder and not the src folder.

Author: hudasyed

docs/documentation/stories/proxy.md

@@ -26,7 +26,7 @@ We can then add the `proxyConfig` option to the serve target:
     "builder": "@angular-devkit/build-angular:dev-server",
     "options": {
       "browserTarget": "your-application-name:build",
-      "proxyConfig": "src/proxy.conf.json"
+      "proxyConfig": "proxy.conf.json"
     },
 ```
 
@@ -183,4 +183,4 @@ function setupForCorporateProxy(proxyConfig) {
 module.exports = setupForCorporateProxy(proxyConfig);
 ```
 
-This way if you have a `http_proxy` or `HTTP_PROXY` environment variable defined, an agent will automatically be added to pass calls through your corporate proxy when running `npm start`.
+This way if you have a `http_proxy` or `HTTP_PROXY` environment variable defined, an agent will automatically be added to pass calls through your corporate proxy when running `npm start`.