fix online code-exercise issue, and optimize readme

Author: Sunrisepeak

.devcontainer/devcontainer.json

@@ -13,5 +13,5 @@
   },
   "remoteUser": "vscode",
   "postCreateCommand": "/bin/bash .devcontainer/postCreate.sh",
-  "postAttachCommand": "xlings checker"
+  "postAttachCommand": "d2x checker"
 }

.devcontainer/postCreate.sh

@@ -9,4 +9,11 @@ if ! command -v xlings >/dev/null 2>&1; then
   curl -fsSL https://d2learn.org/xlings-install.sh | bash
 fi
 
-echo "xlings installed"
+echo "xlings installed"
+
+echo "Installing dependencies (d2x and ...) by xlings..."
+
+source ~/.bashrc
+xlings install --verbose
+
+echo "Dependencies installed"

.github/workflows/online-ebook.yml

@@ -40,17 +40,23 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
-      - name: Install mdBook by Xlings
+
+      - name: Install Xlings
+        env:
+          XLINGS_NON_INTERACTIVE: 1
         run: |
           curl -fsSL https://d2learn.org/xlings-install.sh | bash
-          export PATH=/home/xlings/.xlings_data/bin:$PATH
-          xlings install mdbook@${MDBOOK_VERSION} --global -y
+          echo "PATH=$HOME/.xlings/subos/current/bin:$PATH" >> "$GITHUB_ENV"
+
+      - name: Install mdBook
+        run: xlings install mdbook@${MDBOOK_VERSION} -y
+
       - name: Setup Pages
         id: pages
         uses: actions/configure-pages@v4
+
       - name: Build with mdBook
         run: |
-          export PATH=/home/xlings/.xlings_data/bin:$PATH
           ./build.sh
       - name: Upload artifact
         uses: actions/upload-pages-artifact@v3

README.md

@@ -67,6 +67,7 @@ irm https://d2learn.org/xlings-install.ps1.txt | iex
 </details>
 
 ```bash
+xlings install d2x -y
 d2x install d2mcpp
 cd d2mcpp
 d2x checker

README.zh.hant.md

@@ -67,6 +67,7 @@ irm https://d2learn.org/xlings-install.ps1.txt | iex
 </details>
 
 ```bash
+xlings install d2x -y
 d2x install d2mcpp
 cd d2mcpp
 d2x checker

README.zh.md

@@ -67,6 +67,7 @@ irm https://d2learn.org/xlings-install.ps1.txt | iex
 </details>
 
 ```bash
+xlings install d2x -y
 d2x install d2mcpp
 cd d2mcpp
 d2x checker

book/en/src/README.md

@@ -63,6 +63,7 @@ irm https://d2learn.org/xlings-install.ps1.txt | iex
 </details>
 
 ```bash
+xlings install d2x -y
 d2x install d2mcpp
 cd d2mcpp
 d2x checker

book/src/README.md

@@ -63,6 +63,7 @@ irm https://d2learn.org/xlings-install.ps1.txt | iex
 </details>
 
 ```bash
+xlings install d2x -y
 d2x install d2mcpp
 cd d2mcpp
 d2x checker