Document the link check command

.github/workflows/link-check.yml

@@ -15,6 +15,18 @@ jobs:
       - name: Run Lychee Link Checker
         uses: lycheeverse/lychee-action@v1
         with:
+        # These args ensure that all relevant links are checked, without flaky failures.
+        # 
+        # 1. The --remap helps resolve links which don't list their file extension since all relevant files are .mdx. 
+        #   It also accounts for headings in relative links. Ex. [abc](./file#header) -> .../file.mdx#header
+        # 2. TODO: When the /zh/ sections are all translated, please remove "--exclude '.*/zh/.*".
+        #    This is a temporary measure since not all pages have been translated yet, but the links are still there.
+        # 3. --exclude '^(file:|[./]).*\.html$' - This section of exclusions avoids file paths for resources which are
+        #   not actually relative links. They work at runtime by accessing the 'public' folder.
+        # 4. Other exclusions avoid flaky failures (from slow sites) or acceptable failures (from fake urls).
+        # 5. --accept '403,401,429' - These errors generally mean the link works, but our tool can't access them.
+        # 6. --retry-wait-time - The time in seconds to wait before trying again if we get a 429 error.
+        # 7. --max-retries - How many times we're willing to try again before failing the link.
           args: >
             --remap '(^[^.#]+)(\.?)(#.*)?$ $1.mdx$3'
             --exclude '.*/zh/.*'