add not about custom tests executiong to the readme/help

tasks/test/browser/README.md

@@ -21,9 +21,18 @@ Browser tests are written just like server tests, they are just executed differe
 starting the test runner
 ========================
 
-Under the covers this command uses the `test:dev` task from kibana. This task sets-up
-a test runner that will watch your code for changes and rebuild your tests when necessary.
-You access the test runner through a browser that it starts itself (via Karma).
+Under the covers this command uses the `test:browser` task from kibana. This will execute
+your tasks once and exit when complete.
+
+When run with the `--dev` option, the command uses the `test:dev` task from kibana. 
+This task sets-up a test runner that will watch your code for changes and rebuild your 
+tests when necessary. You access the test runner through a browser that it starts itself 
+(via Karma).
+
+If your plugin consists of a number of internal plugins, you may wish to keep the tests
+isolated to a specific plugin or plugins, instead of executing all of the tests. To do this,
+use `--plugins` and passing the plugins you would like to test. Muliple plugins can be
+specified by separating them with commas.
 
 
 running the tests

tasks/test/server/README.md

@@ -23,6 +23,15 @@ running the tests
 Running the server tests is simple, just execute `npm run test:server` in your terminal
 and all of the tests in your server will be run.
 
+By default, the runner will look for tests in `server/**/__tests__/**/*.js`. If you'd prefer to
+use a different collection of globs and files, you can specify them after the `npm run test:server`
+task, like so:
+
+`npm run test:server 'plugins/myplugins/server/__tests__/**/*.js'`
+
+NOTE: quoting the glob pattern is not required, but helps to avoid issues with globbing expansion
+in your shell.
+
 
 focus on the task at hand
 =========================