Fix broken external links #843
Description
As of 2021-08-21, here are the broken external links:
request exceeded our ExternalTimeout --- docs/what-is-grpc/faq/index.html --> https://corner.squareup.com/2015/02/grpc.html
Non-OK status: 404 --- docs/languages/csharp/basics/index.html --> https://github.com/Reactive-Extensions/Rx.NET/blob/master/Ix.NET/Source/System.Interactive.Async/IAsyncEnumerator.cs
Non-OK status: 404 --- docs/languages/objective-c/oauth2/index.html --> https://github.com/grpc/grpc/tree/
Non-OK status: 404 --- docs/languages/objective-c/oauth2/index.html --> https://grpc-test.sandbox.google.com
request exceeded our ExternalTimeout --- blog/ga-announcement/index.html --> https://corner.squareup.com/2015/02/grpc.html
Non-OK status: 404 --- blog/ga-announcement/index.html --> https://github.com/GoogleCloudPlatform/java-docs-samples/tree/master/speech/grpc
Non-OK status: 404 --- blog/cmake-improvements/index.html --> https://github.com/grpc/grpc/blob/master/test/distrib/cpp/run_distrib_test_raspberry_pi.sh
Non-OK status: 404 --- blog/grpc-go-perf-improvements/index.html --> https://github.com/grpc/grpc-go/compare/master...MakMukhi:http_greeter
Non-OK status: 404 --- blog/grpc-go-perf-improvements/index.html --> https://github.com/grpc/grpc-go/compare/master...MakMukhi:grpc_vs_http
Get "http://www.thisisnotapril.com/": dial tcp: lookup www.thisisnotapril.com: no such host --- blog/hello-pancakes/index.html --> http://www.thisisnotapril.com/
Get "https://www.tcpipguide.com/free/t_TCPConnectionTermination-2.htm": dial tcp 216.92.67.219:443: connect: connection refused --- blog/grpc-on-http2/index.html --> https://www.tcpipguide.com/free/t_TCPConnectionTermination-2.htm
Non-OK status: 404 --- blog/grpc-on-http2/index.html --> https://http2.github.io/http2-spec/#PING
Non-OK status: 404 --- blog/grpc-web-ga/index.html --> https://github.com/grpc/grpc-web/tree/master/net/grpc/gateway/nginx
Non-OK status: 999 --- blog/yikyak/index.html --> https://www.linkedin.com/in/miguel-mendez-008231
Get "https://yikyakapp.com": EOF --- blog/yikyak/index.html --> https://yikyakapp.com
Get "https://deis.com": x509: certificate is valid for *.oneroute.microsoft.com, oneroute.microsoft.com, not deis.com --- blog/helm-grpc/index.html --> https://deis.com
Non-OK status: 404 --- blog/helm-grpc/index.html --> https://github.com/kubernetes/helm/tree/master/_proto/hapi
Non-OK status: 404 --- blog/helm-grpc/index.html --> https://github.com/kubernetes/helm/tree/master/pkg/proto/hapi
Non-OK status: 404 --- blog/helm-grpc/index.html --> https://github.com/kubernetes/helm/tree/master/pkg/helm
Non-OK status: 404 --- blog/meetup-kit/index.html --> https://codelabs.developers.google.com/codelabs/cloud-grpc/index.html
Get "https://pubref.org": EOF --- blog/bazel-rules-protobuf/index.html --> https://pubref.org
Non-OK status: 404 --- blog/bazel-rules-protobuf/index.html --> https://github.com/pubref/rules_protobuf/protobuf/internal/repositories.bzl
Get "https://pubref.org": EOF --- blog/bazel-rules-protobuf/index.html --> https://pubref.org
Non-OK status: 503 --- showcase/index.html --> https://blog.cloudflare.com/road-to-grpc/
Non-OK status: 503 --- showcase/index.html --> https://blog.cloudflare.com/author/junho/