QGB nits + docs for the merge 2

[rach-id]

No description provided.

[rootulp]

Will approve after:

1. File is go formatted
2. Negate check

[rach-id]

@rootulp Sorry, wasn't focusing earlier. The best we can do to refactor is:

	store := ctx.KVStore(k.storeKey)
	if k.CheckLatestAttestationNonce(ctx) {
		if k.GetLatestAttestationNonce(ctx)+1 != nonce {
			panic("not incrementing latest attestation nonce correctly")
		}
		store.Set([]byte(types.LatestAttestationtNonce), types.UInt64Bytes(nonce))
	}
	store.Set([]byte(types.LatestAttestationtNonce), types.UInt64Bytes(nonce))

But I don't think it is worth it.
In fact, we should never panic if the latest nonce doesn't exist in store. Because, if it doesn't, we just proceed and initialize it.
We could add a check nonce == 0 to know that we're initializing state for the first time. However, we might need in the future, after a hard fork, to manually set the first nonce, to a random value that is different from 0, and initialize the store using it.
Let me know what you think.

[rach-id]

If you don't mind, I can rename this PR to contain extra nits that are taken from the Merge PR.

[codecov-commenter]

Codecov Report

Merging #753 (fd8d3e1) into qgb-integration (ab906e5) will increase coverage by 9.75%.
The diff coverage is 73.96%.

@@                 Coverage Diff                 @@
##           qgb-integration     #753      +/-   ##
===================================================
+ Coverage            12.60%   22.36%   +9.75%     
===================================================
  Files                   45       62      +17     
  Lines                 6448     7665    +1217     
===================================================
+ Hits                   813     1714     +901     
- Misses                5550     5809     +259     
- Partials                85      142      +57     

Impacted Files	Coverage Δ
pkg/inclusion/get_commit.go	0.00% <0.00%> (ø)
pkg/prove/querier.go	0.00% <0.00%> (ø)
x/payment/types/tx.pb.gw.go	0.00% <0.00%> (ø)
x/qgb/keeper/hooks.go	36.11% <0.00%> (ø)
x/qgb/keeper/keeper_data_commitment.go	0.00% <ø> (ø)
x/qgb/keeper/keeper_valset.go	27.11% <ø> (ø)
x/qgb/keeper/query_valset.go	0.00% <ø> (ø)
x/qgb/types/genesis.go	70.96% <ø> (ø)
x/qgb/types/keys.go	0.00% <ø> (ø)
x/qgb/types/msgs.pb.gw.go	0.00% <0.00%> (ø)
... and 24 more

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[evan-forbes]

nice additions