Add outdated component to outdated documents (#25)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- [Outdated component style reference](https://mui.com/material-ui/react-alert/)

- Added [`Translate` component](https://docusaurus.io/docs/next/docusaurus-core#translate) to `Outdated` so it can be localized.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- One way to check for the specific outdated documents: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The Chinese documents that are outdated (latest commit is ealier than laster commit of English version):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>

check_outdated.sh

@@ -0,0 +1,38 @@
+#!/bin/bash
+
+# The script takes two params: 
+#     version: "latest" or a specific version number
+#     locale
+# This script checks if a specific locale version of document is up to date with English version
+# If latest commit timestamp of English version is greater than the specific locale version,
+# The specific locale version document will be marked as outdated
+
+set -xe
+
+if sed --version 2>/dev/null | grep -q GNU; then
+    SED_INPLACE="sed -i"
+else
+    SED_INPLACE="sed -i ''"
+fi
+version="$1"
+locale="$2"
+cur_path=`pwd`
+cd .tmp/upstream-docs-"$version"
+
+for file in `find ./docs/content/doc -name "*.${locale}.md"`; do
+    file_en="${file/.${locale}/.en-us}"
+    if [ ! -f "$file_en" ]; then
+        continue
+    fi
+    latest_commit_time_en=$(git log -1 --format=%ct "$file_en")
+    latest_commit_time_locale=$(git log -1 --format=%ct "$file")
+    if [ -z "$latest_commit_time_locale" ]; then
+        continue
+    fi
+    if [[ "$latest_commit_time_en" -gt "$latest_commit_time_locale" ]]; then
+        echo "file: $file, lastest commit timestamp: $latest_commit_time_en (en ver), $latest_commit_time_locale ($locale ver)"
+        $SED_INPLACE '1s/---/---\nisOutdated: true/' $file
+    fi
+done
+
+cd "$cur_path"