BHs readme nits (#2754)

* Correct BH readme

* Zombienet renaming

* TOC

* Apply suggestions from code review

Co-authored-by: Adrian Catangiu <adrian@parity.io>

* Updated REAMDE.md

* Alice -> Bob for e2e

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Co-authored-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: parity-processbot <>