Better discoverability of gRPC examples

[ppcano]

We document gRPC in two different places:

1 - Using k6 / Protocols / gRPC

2 - k6 gRPC API

When looking at k6 gRPC API(2), I could not find the examples on Using k6/gRPC.

For better discoverability, we should give more visibility to these examples within the k6 gRPC API docs.