docs(v2): i18n doc + polish (#4014)

* add some initial i18n doc

* i18n doc progress

* i18n tutorial progress

* i18n tutorial progress

* polish Crowdin docs

* i18n sidebar in guides

* polish crowdin doc

* update Crowdin doc a bit

* fix annoying relative link to global site resource in template (breaks i18n tutorial)

* template: use simpler export for homepage

* add markdown page example

* rename mdx.md to interactiveDoc.mdx

* update bootstrap/facebook templates too

* sync init template package scripts

* add slug frontmatter doc

* improve i18n doc

* complete i18n doc

* temporarily enable the localeDropdown

* doc typo

* improve the i18n doc

* Add Git i18n doc

* add missing "--" for npm run options (unfortunately they don't get stripped by npm2yarn, and are required foor npm)

* improve a bit the Crowdin doc

packages/docusaurus-init/templates/bootstrap/docs/doc1.md

@@ -29,9 +29,9 @@ To serve as an example page when styling markdown based Docusaurus sites.
 
 ## Emphasis
 
-Emphasis, aka italics, with *asterisks* or _underscores_.
+Emphasis, aka italics, with _asterisks_ or _underscores_.
 
-Strong emphasis, aka bold, with **asterisks** or __underscores__.
+Strong emphasis, aka bold, with **asterisks** or **underscores**.
 
 Combined emphasis with **asterisks and _underscores_**.
 
@@ -43,16 +43,18 @@ Strikethrough uses two tildes. ~~Scratch this.~~
 
 1. First ordered list item
 1. Another item
-   - Unordered sub-list.
+
+- Unordered sub-list.
+
 1. Actual numbers don't matter, just that it's a number
-   1. Ordered sub-list
+1. Ordered sub-list
 1. And another item.
 
-* Unordered list can use asterisks
+- Unordered list can use asterisks
 
-- Or minuses
+* Or minuses
 
-+ Or pluses
+- Or pluses
 
 ---
 
@@ -88,10 +90,9 @@ Reference-style: ![alt text][logo]
 
 [logo]: https://github.com/adam-p/markdown-here/raw/master/src/common/images/icon48.png 'Logo Title Text 2'
 
-Images from any folder can be used by providing path to file. Path should be relative to markdown file.
-
-![img](../static/img/logo.svg)
+Images from any folder can be used by providing path to file. Path should be relative to the original markdown file or absolute to the `/static` folder.
 
+![img](/img/logo.svg)
 
 ---
 

packages/docusaurus-init/templates/bootstrap/docs/interactiveDoc.mdx

@@ -5,13 +5,23 @@ title: Powered by MDX
 
 You can write JSX and use React components within your Markdown thanks to [MDX](https://mdxjs.com/).
 
-export const Highlight = ({children, color}) => ( <span style={{
+The `.mdx` extension is not required, but will enable better support from tooling (IDE, Prettier...).
+
+export const Highlight = ({children, color}) => (
+  <span
+    style={{
       backgroundColor: color,
       borderRadius: '2px',
       color: '#fff',
       padding: '0.2rem',
-    }}>{children}</span> );
+    }}
+    onClick={() => alert('Highlight pressed!')}>
+    {children}
+  </span>
+);
 
-<Highlight color="#25c2a0">Docusaurus green</Highlight> and <Highlight color="#1877F2">Facebook blue</Highlight> are my favorite colors.
+<Highlight color="#25c2a0">Docusaurus green</Highlight> and <Highlight color="#1877F2">
+  Facebook blue
+</Highlight> are my favorite colors.
 
 I can write **Markdown** alongside my _JSX_!