Feature/add i18n support&zh-cn Translation init. (#133)

* Update: Add i18n support.

* Update: Fix github action.

* Fix install mdbook action.

* Update: Add zh-cn.po

* Update: Add translation tutorial to Readme.

.github/workflows/install-mdbook/action.yml

@@ -13,3 +13,7 @@ runs:
     - name: Install mdbook-last-changed
       run: cargo install mdbook-last-changed --locked --version 0.1.4
       shell: bash
+
+    - name: Install mdbook-i18n-helpers
+      run: cargo install mdbook-i18n-helpers --locked --version 0.1.0
+      shell: bash

.github/workflows/mdbook.yml

@@ -41,9 +41,18 @@ jobs:
       - name: Install mdbook
         uses: ./.github/workflows/install-mdbook
 
-      - name: Build book
+      - name: Build book (English)
         run: mdbook build -d book
 
+      - name: Build all translations
+        run: |
+          for po_lang in $(cat ./LANGUAGES); do
+              echo "::group::Building $po_lang translation"
+              MDBOOK_BOOK__LANGUAGE=$po_lang \
+              mdbook build -d book/$po_lang
+              echo "::endgroup::"
+          done
+
       - name: Setup Pages
         uses: actions/configure-pages@v3
 

LANGUAGES

@@ -0,0 +1 @@
+zh-cn

README.md

@@ -27,6 +27,27 @@ All the Markdown files **MUST** be edited in english. To work locally in english
 
 - Open a PR with your changes.
 
+##### Work locally (translations)
+
+To work with translations, those are the steps to update the translated content:
+
+- Run a local server for the language you want to edit: `./translations.sh zh-cn` for instance. If no language is provided, the script will only extract translations from english.
+
+- Open the translation file you are interested in `po/zh-cn.po` for instance. You can also use editors like [poedit](https://poedit.net/) to help you on this task.
+
+- When you are done, you should only have changes into the `po/xx.po` file. Commit them and open a PR.
+  The PR must stars with `i18n` to let the maintainers know that the PR is only changing translation.
+
+The translation work is inspired from [Comprehensive Rust repository](https://github.com/google/comprehensive-rust/blob/main/TRANSLATIONS.md).
+
+##### Initiate a new translation for your language
+
+If you wish to initiate a new translation for your language without running a local server, consider the following tips:
+
+- Execute the command `./translations.sh new xx` (replace `xx` with your language code). This method can generate the `xx.po` file of your language for you.
+- To update your `xx.po` file, execute the command `./translations.sh xx` (replace `xx` with your language code), as mentioned in the previous chapter.
+- If the `xx.po` file already exists (which means you are not initiating a new translation), you should not run this command.
+
 #### Cairo programs
 
 The current book has script that verifies the compilation of all Cairo programs in the book.

book.toml

@@ -6,7 +6,7 @@ src = "src"
 title = "Starknet by Example"
 
 [build]
-extra-watch-dirs = ["listings"]
+extra-watch-dirs = ["listings", "po"]
 
 [preprocessor.gettext]
 after = ["links"]