Add outdated component to outdated documents (#25)

- `git log` needs all commit history to compare latest commit of files, so changed `git clone --depth=1` to `git clone`. This will make the step take longer, so might be improved if there is a better way.

- `src/theme/MDXContent/index.js` is from [ejecting of the component](https://docusaurus.io/docs/swizzling#ejecting) inside `@docusaurus/theme-classic` plugin, and this one is safe to eject according to docusaurus

    ![Screen Shot 2023-06-06 at 12.12.28](/attachments/17a3a84b-cec0-4849-8bd6-9e0471d9536f)

    ![Screen Shot 2023-06-06 at 12.12.15](/attachments/58bba321-3cfb-4a8b-8aeb-84422a06c472)

- [Outdated component style reference](https://mui.com/material-ui/react-alert/)

- Added [`Translate` component](https://docusaurus.io/docs/next/docusaurus-core#translate) to `Outdated` so it can be localized. [reference](https://docusaurus.io/docs/next/i18n/tutorial#translate-your-react-code)

- One way to check for the specific outdated documents:

    search for `lastest commit timestamp` in [prepare nightly docs and prepare 1.19 docs steps](https://gitea.com/gitea/gitea-docusaurus/actions/runs/74)

# After

The Chinese documents that are outdated (latest commit is ealier than laster commit of English version):

![Screen Shot 2023-06-06 at 13.04.24](/attachments/e5d16267-d8d8-434e-89b1-138d04ec92a3)

![Screen Shot 2023-06-06 at 13.05.07](/attachments/af8f996a-5318-4f89-841f-b27a4903a27d)

![Screen Shot 2023-06-06 at 13.05.14](/attachments/e6aba31b-46ba-4a32-ad81-81007e0f711e)

Reviewed-on: https://gitea.com/gitea/gitea-docusaurus/pulls/25
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: HesterG <hestergong@gmail.com>
Co-committed-by: HesterG <hestergong@gmail.com>

loop_docs.sh

@@ -21,7 +21,7 @@ $SED_INPLACE 's/{{< min-go-version >}}/1.20/' docs/installation/from-source.en-u
 
 $SED_INPLACE 's/"version":.*/"version":"1.20-dev"/' static/latest-swagger.json
 
-for file in `find ./docs/ -name "*.md"`; do
+for file in `find ./docs -name "*.md"`; do
     # hide hugo toc
     $SED_INPLACE 's/{{< toc >}}//' $file
     $SED_INPLACE 's/dl.gitea.com\/gitea\/{{< version >}}/dl.gitea.com\/gitea\/main/g' $file
@@ -44,6 +44,8 @@ for file in docs/*; do
     rm $file || true
 done
 
-for file in `find ./docs/ -name "*.en-us.md"`; do
+# file names under docs/ and i18n/zh-cn/docusaurus-plugin-content-docs/current/ should be the same for docusaurus 
+# to recognize them as tanslated.
+for file in `find ./docs -name "*.en-us.md"`; do
     mv "${file}" "${file/.en-us/}"
 done