docs: update localization guide

Author: ledsun

LOCALIZING.md

@@ -2,11 +2,13 @@
 
 In computing, localization is the process of adapting software to different languages, regional differences, cultural preferences, and technical requirements of a target audience.
 
-This guide explains how to contribute a new localization to this workshopper. If you are an international user and would like to bring Nodeschool workshops to a broader audience, please consider contributing a localization! It is simple, fun, and enables more people to learn and practice.
+This guide explains how to contribute a new localization to this workshopper. If you are an international user and would like to bring NodeSchool workshops to a broader audience, please consider contributing a localization! It enables more people to learn and practice.
 
 ## Menu
 
-The menu of the workshopper greets the user with a list of problem names. The strings for these names are contained in the top level `menu.json` file. Translations of problem names should be placed in a JSON file inside the `i18n` folder named with the language code, e.g. `es.json`. Use an existing translation file as reference, ensuring it's up to date with the contents of `menu.json`.
+The menu of the workshopper greets the user with a list of problem names. The strings for these names are contained in the top-level `menu.json` file. Translations of problem names should be placed in a JSON file inside the `i18n` folder named with the language code, e.g. `es.json`. Use an existing translation file as a reference, ensuring it is up to date with the contents of `menu.json`.
+
+The workshopper automatically detects languages from the JSON files in `i18n`, so adding this file also adds the language to the `CHOOSE LANGUAGE` menu. You do not need to edit `index.js`.
 
 ```json
 {
@@ -27,7 +29,7 @@ In order to add a localized footer for Spanish, create a `es.md` file inside the
 
 ## Troubleshooting tips
 
-Similarly, workshoppers display troubleshooting tips when the user submits a wrong solution for the exercise. Tips are contained in a [Markdown](https://en.wikipedia.org/wiki/Markdown) file located inside the `i18n` directory, named after the language code, e.g. `troubleshooting-ja.md`.
+Similarly, workshoppers display troubleshooting tips when the user submits a wrong solution for the exercise. Tips are contained in a [Markdown](https://en.wikipedia.org/wiki/Markdown) file located inside the `i18n` directory, named after the language code, e.g. `troubleshooting_ja.md`.
 
 In order to add translated troubleshooting tips for Spanish, create a `troubleshooting_es.md` file inside the `i18n` directory, containing the translation of the English file `troubleshooting.md`.
 
@@ -38,15 +40,13 @@ The text of each problem and the message printed when the user solves it can be
 ```
 +-- problems
 |   +-- problem-1
-|   |   +-- index.js
 |   |   +-- problem.md
 |   |   +-- problem_ja.md
 |   |   +-- problem_zh-cn.md
 |   |   +-- solution.md
 |   |   +-- solution_ja.md
 |   |   `-- solution_zh-cn.md
 |   +-- problem-2
-|   |   +-- index.js
 |   |   +-- problem.md
 |   |   +-- problem_ja.md
 |   |   +-- problem_zh-cn.md
@@ -63,7 +63,6 @@ In order to add the Spanish localization, we must add new `problem_es.md` and `s
 ```
 +-- problems
 |   +-- problem-1
-|   |   +-- index.js
 |   |   +-- problem.md
 |   |   +-- problem_es.md
 |   |   +-- problem_ja.md
@@ -73,7 +72,6 @@ In order to add the Spanish localization, we must add new `problem_es.md` and `s
 |   |   +-- solution_ja.md
 |   |   `-- solution_zh-cn.md
 |   +-- problem-2
-|   |   +-- index.js
 |   |   +-- problem.md
 |   |   +-- problem_es.md
 |   |   +-- problem_ja.md
@@ -87,10 +85,10 @@ In order to add the Spanish localization, we must add new `problem_es.md` and `s
 
 This is probably the most complex and time consuming task of localizing a workshopper, as problems often interleave paragraphs of text, code snippets and suggestions.
 
-Please remember to use welcoming and inclusive language. The [Contributor Covenant](http://contributor-covenant.org/) offers guidelines if you're unsure.
+Please remember to use welcoming and inclusive language. The [Contributor Covenant](https://www.contributor-covenant.org/) offers guidelines if you're unsure.
 
 ## Testing
 
-In order to test a translation, launch the workshopper and choose the desired language selecting the menu option `CHOOSE LANGUAGE`. If you don't see the language you contributed listed in the options, chances are you didn't save your updates to the list of languages in the `index.js`.
+Run `npm test`, then launch the workshopper and choose the desired language by selecting the menu option `CHOOSE LANGUAGE`. Check that the menu, problem descriptions, solutions, troubleshooting tips, and footer are displayed correctly. If the language is not listed, check that its JSON file exists in `i18n` and has the correct language-code filename.
 
 Once you're satisfied with the results, commit your changes and push to your repo, then submit a PR to the main workshopper repo!