doc: fix data-plane-api link in v2_overview.rst. (#498)
doc: fix data-plane-api link in v2_overview.rst. (#498)

Signed-off-by: Harvey Tuch <c185081708e02336640916420d0c772668570de5@google.com>
lyft/envoy-api,jrajahalme/envoy-api,jrajahalme/envoy-api,lyft/envoy-api,lyft/envoy-api,jrajahalme/envoy-api,jrajahalme/envoy-api