Documentation for creating custom router with rust plugins.

[golfingal72]

Just an FYI:

I created this issue #5237

I found a solution by forcing the serde_v8 to compile with opt-level=1.

Building a release version which requires compiling everything from the base repository was causing failures in the router-bridge code and the service could not start up. I spent days figuring this out, so I thought I would share.