feat: add AC about pegged orders and the interaction with vAMM orders

Signed-off-by: Elias Van Ootegem <elias@vega.xyz>

protocol/0090-VAMM-automated_market_maker.md

@@ -337,3 +337,5 @@ At market settlement, an AMM's position will be settled alongside all others as
 - With an existing book consisting solely of one vAMM (at any fair price) a new vAMM entering the market at a differing base price to the existing vAMM's current price, with upper and lower bounds set such that the entire structure is separate to the existing vAMM (e.g. the incoming vAMM's lower price is greater than the existing vAMM's upper price), a trade occurs between the two AMMs leaving at least one of them at the extreme edge of their quoting range. (<a name="0090-VAMM-034" href="#0090-VAMM-034">0090-VAMM-034</a>)
 
 - With two vAMMs existing on the market, and no other orders, both of which have the same fair price, another counterparty placing a large buy order for a given volume, followed by a large sell order for the same volume, results in the vAMMs both taking a position and then returning to `0` position, with a balance increase equal to the maker fees received plus those for the incoming trader crossing the spread. (<a name="0090-VAMM-035" href="#0090-VAMM-035">0090-VAMM-035</a>)
+
+- With an existing book consisting solely of one vAMM, pegged orders referencing best bid/best ask remain deployed, pegged to their pegs, where the highest buy/sell vAMM order price acts as the best bid, or best ask peg respectively. (<a name="0090-VAMM-036" href="#0090-VAMM-036">0090-VAMM-036</a>)