docs: adds information about the Envoy tracer from Instana #6371 (#6416)
docs: adds information about the Envoy tracer from Instana #6371 (#6416)

Signed-off-by: Christoph Engelbert <b1c1d8736f20db3fb6c1c66bb1455ed43909f0d8@noctarius.com>

envoyproxy/envoy,istio/envoy,jrajahalme/envoy,envoyproxy/envoy,eklitzke/envoy,dnoe/envoy,jrajahalme/envoy,dnoe/envoy,envoyproxy/envoy,lyft/envoy,dnoe/envoy,envoyproxy/envoy,envoyproxy/envoy-wasm,istio/envoy,eklitzke/envoy,istio/envoy,lyft/envoy,envoyproxy/envoy-wasm,jrajahalme/envoy,envoyproxy/envoy-wasm,lizan/envoy,envoyproxy/envoy-wasm,istio/envoy,envoyproxy/envoy,envoyproxy/envoy-wasm,dnoe/envoy,jrajahalme/envoy,envoyproxy/envoy,lizan/envoy,envoyproxy/envoy-wasm,jrajahalme/envoy,lizan/envoy,envoyproxy/envoy,envoyproxy/envoy,eklitzke/envoy,envoyproxy/envoy,eklitzke/envoy,eklitzke/envoy,lyft/envoy,lyft/envoy,envoyproxy/envoy,lizan/envoy,envoyproxy/envoy,lizan/envoy,eklitzke/envoy,istio/envoy,istio/envoy,jrajahalme/envoy,envoyproxy/envoy,envoyproxy/envoy-wasm,istio/envoy,lyft/envoy,lyft/envoy,lizan/envoy,dnoe/envoy