Documentation: add information about different physSim and routers we have.

[nikolayilyin]

Currently only JDEQSim and R5 are mentioned in the latest documentation, but we also have BPRSim, ParBPRSim, CCHRoutingAssigment and additional routers - CCH, GH.

One needs to add some information into documentation about mentioned routers and physSim implementations

[nikolayilyin]

Also in the beam-template according config keys should have comments with all possible values

[HoneyTauOverTwo]

beam-template already has comments about these:

physSim beam-template.conf#L478: values: JDEQSim, BPRSim, PARBPRSim, CCHRoutingAssignment

Routing beam-template.conf#L895: values: R5, staticGH, quasiDynamicGH, nativeCCH (Linux Only)

Documentation for phySim and router indeed needs updating

[HoneyTauOverTwo]

I identified the relevant java and scala files related to physics simulation (working on routers), but I might need some help to actually write the documentation.

For instance, what BPR and CCH stand for.

From what I understand, BPR, it is an alternative for Java Discrete Event Queue Simulator (JDEQ) from MATSim. It was implemented by Dima so might need his help.

I guess I'd have to know the difference, advantages, disadvantages of each approach.

As for CCHRoutingAssignment, it appears to be one that bypasses physics simulation ignoring congestion and such.