Support page-relative aliases

[chalin]

• Prep for continued work on Post specs update: address 404s and reenabled all checks #3392
• Provides support for page-relative aliases that either:
  • Do not start with "/"
  • Start with one or more "../"
• Includes a workaround for misformatted semconv alias paths (that are missing a leading /)

The only file affected is _redirects and the changes aren't significant (a leading or trailing / was added):

diff --git a/_redirects b/_redirects
index d6419903f..e22095996 100644
--- a/_redirects
+++ b/_redirects
@@ -101,7 +101,7 @@
 /docs/instrumentation/rust/examples/ https://github.com/open-telemetry/opentelemetry-rust/tree/main/examples
 /docs/instrumentation/swift/examples/ https://github.com/open-telemetry/opentelemetry-swift/tree/main/Examples
 /blog/2023/gc-elections-2023        /blog/2023/gc-elections/
-/blog/2023/additional-collector-sig/ /blog/2023/new-apac-meetings/
+/blog/2023/additional-collector-sig /blog/2023/new-apac-meetings/
 /blog/2023/end-user-q-and-a-series-otel-and-graphql /blog/2023/end-user-q-and-a-01/
 /blog/2023/otel-end-user-q-and-a-series-otel-and-graphql /blog/2023/end-user-q-and-a-01/
 /blog/2023/otel-end-user-discussions-january-2023 /blog/2023/end-user-discussions-01/
@@ -130,7 +130,7 @@ docs/specs/semconv/general/events-general /docs/specs/semconv/general/events/
 /docs/demo/feature_flags            /docs/demo/feature-flags/
 /docs/demo/demo_features            /docs/demo/features/
 /docs/demo/services/frauddetectionservice /docs/demo/services/fraud-detection/
-docs/demo/services/frontendproxy    /docs/demo/services/frontend-proxy/
+/docs/demo/services/frontendproxy   /docs/demo/services/frontend-proxy/
 /integrations                       /ecosystem/integrations/
 /docs/demo/kubernetes_deployment    /docs/demo/kubernetes-deployment/
 /docs/operator                      /docs/kubernetes/operator/

Redirect tests (a sampling):

• https://deploy-preview-3417--opentelemetry.netlify.app/blog/2022/gc-elections-2022-list-of-candidates
• https://deploy-preview-3417--opentelemetry.netlify.app/docs/concepts/instrumenting-library
• https://deploy-preview-3417--opentelemetry.netlify.app/docs/instrumentation/java/extensions
• https://deploy-preview-3417--opentelemetry.netlify.app/docs/instrumentation/js/api/propagation