Fix Broken Restart Documentation
Add Doc For Particle Per SuperCell Plugin

Introduced in #163,
[wiki](https://github.com/ComputationalRadiationPhysics/picongpu/wiki/PIConGPU-Plugins)
entry still missing
Add --checkpoints
Add --hdf5.restart-file which is currently required

- use a unique name different from the output name
Fix Typos and Outdated Option
Merge pull request #357 from ax3l/doc-updateTBG

Doc update tbg