Update testing instructions for developer and maintainer guides

The updatetest and updatetestwin scripts have been added for developers
to update the expected output for all test sites.

Also, testing instructions for the developer and maintainer guides
assume that there is only one test site.

Let's update the developer and maintainer guides to include usage
instructions for the test site update scripts. Let's also generalize
the testing instructions for multiple test sites.

docs/devGuide/devGuide.md

@@ -120,8 +120,8 @@ A: If your npm version is v6.0.0 or higher, there is a change in behaviour on ho
 Our test script does the following:
 
 1. Lints the code for any code and style errors using ESLint.
-1. Builds the test site found in `test/test_site/`.
-1. Compares the HTML files generated with the HTML files in `test/test_site/expected/`.
+1. Builds the test sites whose directory names are listed in `test/functional/test_sites`.
+1. For each test site, compares the HTML files generated with the HTML files in its `expected` directory.
 
 #### Running tests
 
@@ -136,20 +136,41 @@ $ npm run test
 For Windows users:
 
 ```
-$ npm run testwin
+> npm run testwin
 ```
 
 #### Updating tests
 
 When adding new features, updating existing features or fixing bugs, you should update the expected site to reflect the changes.
 
+You may use the following script to update the expected sites:
+
+For Unix:
+
+```
+$ npm run updatetest
+```
+
+For Windows users:
+
+```
+> npm run updatetestwin
+```
+<box type="warning">
+  You should always check that the output generated is correct before committing your changes to the expected site.
+</box>
+
 ##### Changes to existing features
 
-Simply update the expected HTML files in `test/test_site/expected/` to reflect the changes.
+Simply update the expected HTML files for each test site to reflect the changes.
 
 ##### New features
 
-Add new site content into the `test/test_site/` folder to demonstrate the new feature. Ensure that the new content is included in the test site so that your feature will be tested when `markbind build` is run on the test site. Remember to update the expected HTML files in `test/test_site/expected/`.
+Add new site content into an existing test site or create a new test site to demonstrate the new feature. Ensure that the new content is included in the test site so that your feature will be tested when `markbind build` is run on the test site. Remember to update the expected HTML files for the test site.
+
+<box type="info">
+  When creating a new test site, the directory name of the new test site should be added to <code>test/functional/test_sites</code>.
+</box>
 
 ### Using ESLint
 

docs/devGuide/maintainerGuide.md

@@ -115,13 +115,11 @@ $ git commit -m 'Update vue-strap version to v2.0.1-markbind.XYZ'
 2. Rebuild the test files.
 
 ```
-$ cd test/functional/
+# on Unix
+$ npm run updatetest
 
-# for each test site
-$ cd <TEST_SITE_NAME>
-$ markbind build
-$ cp _site/* expected/
-$ cd ..
+# on Windows
+> npm run updatetestwin
 ```
 
 When rebuilding the expected test files, ensure that **only** the version number is updated. For example, this is correct: