Merge pull request #10991 from mehrdada/cpp-doc-fixes

include/grpc++/create_channel.h

include/grpc++/create_channel_posix.h

...e/grpc++/ext/health_check_service_server_builder_option.h

include/grpc++/ext/proto_server_reflection_plugin.h

include/grpc++/grpc++.h

include/grpc++/health_check_service_interface.h

include/grpc++/impl/codegen/client_context.h

include/grpc++/resource_quota.h

include/grpc++/security/auth_metadata_processor.h

include/grpc++/security/credentials.h

include/grpc++/security/server_credentials.h

include/grpc++/server.h

include/grpc++/server_builder.h

include/grpc++/server_posix.h

include/grpc++/support/channel_arguments.h

include/grpc++/support/error_details.h

include/grpc++/support/slice.h

include/grpc++/test/server_context_test_spouse.h