docs: Validate JSON snippets (settings, keymap, tasks, etc) (#40043)

Closes #ISSUE

Release Notes:

- N/A *or* Added/Fixed/Improved ...

docs/src/languages/c.md

@@ -17,7 +17,7 @@ CompileFlags:
 
 By default clang and gcc will recognize `*.C` and `*.H` (uppercase extensions) as C++ and not C and so Zed too follows this convention. If you are working with a C-only project (perhaps one with legacy uppercase pathing like `FILENAME.C`) you can override this behavior by adding this to your settings:
 
-```json
+```json [settings]
 {
   "file_types": {
     "C": ["C", "H"]
@@ -40,7 +40,7 @@ See [Clang-Format Style Options](https://clang.llvm.org/docs/ClangFormatStyleOpt
 
 You can trigger formatting via {#kb editor::Format} or the `editor: format` action from the command palette or by adding `format_on_save` to your Zed settings:
 
-```json
+```json [settings]
   "languages": {
     "C": {
       "format_on_save": "on",
@@ -69,7 +69,7 @@ You can use CodeLLDB or GDB to debug native binaries. (Make sure that your build
 
 ### Build and Debug Binary
 
-```json
+```json [debug]
 [
   {
     "label": "Debug native binary",