Adding Doc for Limit Integrations (#660)

docs/contracts/uniswapx/guides/createFiller.md

@@ -10,7 +10,7 @@ There are two components to integrating as a filler: defining a filler execution
 
 ## 1. Defining a Filler Execution Strategy
 
-To execute a discovered order, a filler needs to call one of the `execute` methods ([source](https://github.com/Uniswap/UniswapX/blob/v1.1.0/src/reactors/BaseReactor.sol#L31)) of the Dutch Order Reactor, providing it with the orders to execute.
+To execute a discovered order, a filler needs to call one of the `execute` methods ([source](https://github.com/Uniswap/UniswapX/blob/v1.1.0/src/reactors/BaseReactor.sol#L31)) of an Order Reactor, providing it with the orders to execute.
 
 The simplest fill strategy is called `Direct Filler`, where the trade is executed directly against tokens held in the fillers address. To use this strategy, a filler can simply approve the order's output tokens to the reactor and call `execute` or `executeBatch` from their address. (see [source](https://github.com/Uniswap/UniswapX/blob/v1.1.0/src/reactors/BaseReactor.sol#L35)):
 
@@ -41,9 +41,9 @@ executor.execute(order, fillData);
 
 For convenience, we’ve provided an [example Executor Contract](https://github.com/Uniswap/UniswapX/tree/v1.1.0/src/sample-executors) which demonstrates how a filler could implement a strategy that executes a UniswapX order against a Uniswap V3 pool.
 
-## 2. Retrieve & Execute Signed Orders
+## 2A. Retrieve & Execute Signed Dutch Orders
 
-All signed orders created through the Uniswap UI will be available via the UniswapX Orders Endpoint. We have [swagger documentation](https://api.uniswap.org/v2/uniswapx/docs) but see below for a quick example curl.
+All signed Dutch Orders created through the Uniswap UI will be available via the UniswapX Orders Endpoint. We have [swagger documentation](https://api.uniswap.org/v2/uniswapx/docs) but see below for a quick example curl.
 
 ```
 GET https://api.uniswap.org/v2/orders?orderStatus=open&chainId=1&limit=1
@@ -56,4 +56,11 @@ It’s up to the individual filler to architect their own systems for finding an
 3. Determine which orders you would like to execute
 4. Send a new transaction to the [execute](https://github.com/Uniswap/UniswapX/blob/a2025e3306312fc284a29daebdcabb88b50037c2/src/reactors/BaseReactor.sol#L29) or [executeBatch](https://github.com/Uniswap/UniswapX/blob/a2025e3306312fc284a29daebdcabb88b50037c2/src/reactors/BaseReactor.sol#L37) methods of the [Dutch Order Reactor](https://github.com/Uniswap/UniswapX/blob/main/src/reactors/DutchOrderReactor.sol) specifying the signed orders you’d like to fill and the address of your executor contract
 
-If the order is valid, it will be competing against other fillers attempts to execute it in a gas auction. For this reason, we recommend submitting these transactions through a service like [Flashbots Protect](https://docs.flashbots.net/flashbots-protect/overview).
+## 2B. Retrieve & Execute Signed Limit Orders
+The process for retrieving and executing limit orders is the same as Dutch Orders above except that Limit Orders will be retrieved from the [Limit Orders Endpoint](https://api.uniswap.org/v2/limit-orders) (full API docs [here](https://api.uniswap.org/v2/uniswapx/docs)) and executed against the [Limit Order Reactor](https://github.com/Uniswap/UniswapX/blob/main/src/reactors/LimitOrderReactor.sol). The process is: 
+
+1. Call `GET` on the `/limit-orders` of the UniswapX Limit Orders Endpoint as written above, to retrieve open signed orders
+2. Decode returned orders using the [UniswapX SDK](https://github.com/Uniswap/UniswapX-sdk/#parsing-orders)
+3. Send a new transaction to the [execute](https://github.com/Uniswap/UniswapX/blob/a2025e3306312fc284a29daebdcabb88b50037c2/src/reactors/BaseReactor.sol#L29) or [executeBatch](https://github.com/Uniswap/UniswapX/blob/a2025e3306312fc284a29daebdcabb88b50037c2/src/reactors/BaseReactor.sol#L37) methods of the [Limit Order Reactor](https://github.com/Uniswap/UniswapX/blob/main/src/reactors/LimitOrderReactor.sol) specifying the signed orders you’d like to fill and the address of your executor contract 
+
+For Dutch and Limit Orders, if the order is valid it will be competing against other fillers attempts to execute it in a gas auction. For this reason, we recommend submitting these transactions through a service like [Flashbots Protect](https://docs.flashbots.net/flashbots-protect/overview).