Use sed pre-processing instead of --remap for root-relative links

Replace the lychee --remap flag with a sed pre-processing step
(matching the approach used in MSAL Java) that rewrites
root-relative markdown links like [text](/path) to
[text](https://learn.microsoft.com/path) before lychee runs.

The --remap regex approach couldn't intercept root-relative links
before lychee's own root-relative resolver rejected them.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Dickson-Mwendia

.github/workflows/linkvalidator.yml

@@ -16,13 +16,19 @@ jobs:
     steps:
       - uses: actions/checkout@v3
 
+      - name: Resolve root-relative links for checking
+        run: |
+          # Convert root-relative markdown links like [text](/path) to [text](https://learn.microsoft.com/path)
+          # so lychee can validate them. This only modifies the CI checkout copy.
+          find . -name '*.md' -exec sed -i -E 's|\]\(/|\](https://learn.microsoft.com/|g' {} +
+
       - name: Link Checker
         id: lychee
         uses: lycheeverse/lychee-action@master
         env:
           GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
         with:
-          args: --accept=200,429,403,502,503 --verbose --no-progress --remap '^/(.+) https://learn.microsoft.com/$1' './**/*.md'
+          args: --accept=200,429,403,502,503 --verbose --no-progress './**/*.md'
           fail: true
 
       - name: Create Issue From File