docs: Ensure the CI passes for docs (#2666)

* Fix docs

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update client/relay-chain-rpc-interface/src/reconnecting_ws_client.rs

Co-authored-by: Davide Galassi <davxy@datawok.net>

* Update cargo.lock with substrate

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update Cargo.lock for polkadot

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

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Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>
Co-authored-by: Davide Galassi <davxy@datawok.net>
Co-authored-by: parity-processbot <>