Add monitoring best practices

[yurishkuro]

e.g.

• the usual process signals like CPU/memory usage, file descriptors, network usage
• Go runtime signals like goroutine count, GC
• Jaeger internals: dropped span count, mem queue size, storage write counts/latencies

[chandresh-pancholi]

Hi,
I have set up jaeger documentation in local. Please let me know what's the content you want me to add in monitoring.

[yurishkuro]

Related: Add metrics documentation #178