Fix lychee checking internal/relative links

Add scheme = ["https", "http"] to lychee.toml so lychee only attempts
to check http/https URLs. Without this, lychee tries to resolve
root-relative paths (/img/..., /page/...) as file URIs and fails.
Internal links are already validated by validate-docs.yml.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: sharadregoti

lychee.toml

@@ -1,6 +1,10 @@
 # Lychee external link checker configuration
 # Docs: https://lychee.cli.rs/usage/configuration/
 
+# Only check http/https URLs — skips root-relative paths (/img/..., /page/...),
+# file paths, mailto:, etc. Internal links are validated by validate-docs.yml.
+scheme = ["https", "http"]
+
 # Only check external URLs — internal links are validated by validate-docs.yml
 exclude = [
   # Tyk-owned domains (covered by internal link checks)