docs: Update C# and C++ configuration pages (#19500)

- Update C# configuration page.
- Fix typo in C++ configuration page.

Release Notes:

- N/A

docs/src/languages/cpp.md

@@ -24,7 +24,7 @@ To use a binary in a custom location, add the following to your `settings.json`:
 }
 ```
 
-If you want to disable Zed looking for a `clangd` binary, you can set `ignore_system-version` to `true`:
+If you want to disable Zed looking for a `clangd` binary, you can set `ignore_system_version` to `true`:
 
 ```json
 {

docs/src/languages/csharp.md

@@ -17,7 +17,21 @@ The `OmniSharp` binary can be configured in a Zed settings file with:
     "omnisharp": {
       "binary": {
         "path": "/path/to/OmniSharp",
-        "args": ["optional", "additional", "args", "-lsp"]
+        "arguments": ["optional", "additional", "args", "-lsp"]
+      }
+    }
+  }
+}
+```
+
+If you want to disable Zed looking for a `omnisharp` binary, you can set `ignore_system_version` to `true`:
+
+```json
+{
+  "lsp": {
+    "omnisharp": {
+      "binary": {
+        "ignore_system_version": true
       }
     }
   }