Fix statement distribution: forward statements to other peers. (#2146)

* add candidate hash statement circulation span

* add relay-parent to hash-span

* Some typos and misspellings in docs I found, during my studies. (#2144)

* Fix stale link to overseer docs

* Some typos and mispellings in docs/comments

I found during studying how Polkadot works.

* Rococo V1 (#2141)

* Update to latest master and use 30 minutes sessions

* add bootnodes to chainspec

* Update Substrate

* Update chain-spec

* Update Cargo.lock

* GENESIS

* Change session length to one hour

* Bump spec_version to not fuck anything up ;)

Co-authored-by: Erin Grasmick <[email protected]>

* avoid creating duplicate unbacked spans when we see extra statements (#2145)

* improve jaeger spans for statement distribution

* tweak and add failing test for repropagation

* make a change that gets the test passing

* guide: clarify

* remove semicolon

Co-authored-by: Robert Klotzner <[email protected]>
Co-authored-by: Bastian Köcher <[email protected]>
Co-authored-by: Erin Grasmick <[email protected]>