Add breaking changes docs (#34063)

* Add breaking changes docs

Fixes #33996

Add the configuration and TOC changes for publishing the breaking changes articles to the razor compiler.

* Remove non-functioning attributes

The file based meta data isn't working with this folder layout. So, add the metadata to the files directly

See dotnet/razor#11199

Author: BillWagner

.openpublishing.publish.config.json

@@ -63,6 +63,13 @@
       "url": "https://github.com/dotnet/AspNetCore.Docs.Samples",
       "branch": "main",
       "branch_mapping": {}
+    },
+    {
+      "path_to_root": "_razor",
+      "url": "https://github.com/dotnet/razor",
+      "branch": "main",
+      "include_in_build": true,
+      "branch_mapping": {}
     }
   ],
   "branch_target_mapping": {

aspnetcore/docfx.json

@@ -6,6 +6,16 @@
         "exclude": [ "**/includes/**", "***/license.md", "**/obj/**", "***/readme.md", "**/sample/**", "**/samples/**", "_site/**" ], 
         "group": "group1", 
         "src": "."
+      },
+      {
+        "files": [
+            "Compiler Breaking Changes - DotNet 8.md",
+            "Compiler Breaking Changes - DotNet 9.md"
+        ],
+        "exclude": [],
+        "group": "group1", 
+        "src": "../_razor/docs",
+        "dest": "_razor/docs"
       }
     ],
     "resource": [

aspnetcore/toc.yml

@@ -799,6 +799,10 @@ items:
             uid: mvc/controllers/filters
           - name: Razor SDK
             uid: razor-pages/sdk
+          - name: Razor breaking changes since .NET 8
+            href: ../_razor/docs/Compiler%20Breaking%20Changes%20-%20DotNet%208.md
+          - name: Razor breaking changes since .NET 9
+            href: ../_razor/docs/Compiler%20Breaking%20Changes%20-%20DotNet%209.md
           - name: View components
             uid: mvc/views/view-components
           - name: View compilation