Merge the microbuild branch from https://github.com/aarnott/Library.Template

Specifically, this merges [df8d6cd from that repo](AArnott/Library.Template@df8d6cd).

Author: AArnott

.github/workflows/docs_validate.yml

@@ -6,12 +6,16 @@ on:
 
 jobs:
   build:
-    name: 📚 docfx
+    name: 📚 Doc validation
     runs-on: ubuntu-22.04
     steps:
     - uses: actions/checkout@v4
       with:
         fetch-depth: 0 # avoid shallow clone so nbgv can do its work.
+    - name: 🔗 Markup Link Checker (mlc)
+      uses: becheran/[email protected]
+      with:
+        args: --do-not-warn-for-redirect-to https://learn.microsoft.com*,https://dev.azure.com/*,https://app.codecov.io/*,https://msrc.microsoft.com/*,https://www.microsoft.com/en-us/msrc* -p docfx -i https://aka.ms/onboardsupport,https://aka.ms/spot,https://www.microsoft.com/msrc/cvd,https://www.microsoft.com/msrc
     - name: ⚙ Install prerequisites
       run: |
         ./init.ps1 -UpgradePrerequisites

CONTRIBUTING.md

@@ -27,7 +27,7 @@ You should install the version specified in `global.json` or a later version wit
 the same major.minor.Bxx "hundreds" band.
 For example if 2.2.300 is specified, you may install 2.2.300, 2.2.301, or 2.2.310
 while the 2.2.400 version would not be considered compatible by .NET SDK.
-See [.NET Core Versioning](https://docs.microsoft.com/dotnet/core/versions/) for more information.
+See [.NET Core Versioning](https://learn.microsoft.com/dotnet/core/versions/) for more information.
 
 ## Package restore
 
@@ -49,7 +49,7 @@ msbuild src
 ## Releases
 
 Use `nbgv tag` to create a tag for a particular commit that you mean to release.
-[Learn more about `nbgv` and its `tag` and `prepare-release` commands](https://github.com/dotnet/Nerdbank.GitVersioning/blob/main/doc/nbgv-cli.md).
+[Learn more about `nbgv` and its `tag` and `prepare-release` commands](https://dotnet.github.io/Nerdbank.GitVersioning/docs/nbgv-cli.html).
 
 Push the tag.