nit: suggest mermaid syntax highlighting (#3389)

Co-authored-by: Trajan0x <[email protected]>

.gitattributes

@@ -21,3 +21,5 @@ contrib/opbot/generated/* linguist-generated
 # svg should be treated as a binary https://git.io/JE2VK
 *.svg    binary
 *.sol linguist-language=Solidity
+
+.vscode/*.json linguist-language=jsonc

.github/workflows/lint.yml

@@ -28,6 +28,11 @@ jobs:
         with:
           pattern: '.github/renovate.json' # Regular expression for filename to validate, default to *.json
 
+      - name: jsonc-syntax-check
+        uses: stevieb9/[email protected]
+        with:
+          pattern: .vscode/*.json'
+
 
       - name: yaml-lint
         uses: ibiqlik/action-yamllint@v3

.vscode/extensions.json

@@ -1,12 +1,19 @@
 {
+    // This file (like all vscode metadata files) uses JSON with Comments (JSONC) format, which supports:
+    // - Comments (both single and multi-line)
+    // - Trailing commas
+    // - More lenient syntax than standard JSON
+
     // See https://go.microsoft.com/fwlink/?LinkId=827846 to learn about workspace recommendations.
     // Extension identifier format: ${publisher}.${name}. Example: vscode.csharp
-  
+
     // List of extensions which should be recommended for users of this workspace.
     "recommendations": [
       "dbaeumer.vscode-eslint",
       "editorconfig.editorconfig",
       "juanblanco.solidity",
       "golang.go",
+      "bierner.markdown-mermaid",
+      "bpruitt-goddard.mermaid-markdown-syntax-highlighting",
     ],
-  }
+  }