style image container readme

Author: etpinard

test/image/README.md

@@ -26,7 +26,7 @@ the above evaluates the output of `docker-machine env default`.
 
 ### Step 1: Run the testing container
 
-Plotly.js uses `docker-compose` to ease the creation/stopping/deletion of the testing docker container.
+We use `docker-compose` to ease the creation/stopping/deletion of the testing docker container.
 
 Inside your `plotly.js` directory, run
 
@@ -40,8 +40,8 @@ as listed on [hub.docker.com](https://hub.docker.com/r/plotly/testbed/tags/) and
 
 ### Step 2: Run the image tests
 
-The image testing docker container allows plotly.js developers to (A) run image
-comparison tests, (B) run image export tests and (C) generate baseline
+The image testing docker container allows plotly.js developers to ([A](#a-run-image-comparison-tests) run image
+comparison tests, ([B](#b-run-image-export-tests) run image export tests and ([C](#c-generate-or-update-existing-baseline-image)) generate baseline
 images.
 
 **IMPORTANT:** the image tests scripts do **not** bundle the source files before
@@ -64,10 +64,10 @@ npm run test-image
 ```
 
 which runs all image comparison tests in batch. If some tests fail, compare their outputs
-using `npm run start-image_viewer`.
+by booting up the test image viewer using `npm run start-image_viewer`.
 
 As an alternative to running all image comparison tests at once, you can provide
-a glob as argument to target one or multiple test mocks found in
+a [glob](https://github.com/isaacs/node-glob) as argument to target one or multiple test mocks found in
 [`test/image/mocks`][mocks].
 For example,