fix: Mentioned FilterBy, used FindBy

- Used FindBy since that was what the tutorial used, and also looking for a single Identity.
- Note: There may be a similar rust discrepancy in the Unity pt1 tutorial. It'll work with Filter, but just simply less consistent. Holding off on that since my Rust syntax knowledge !exists.

Author: dylanh724

docs/modules/c-sharp/quickstart.md

@@ -199,7 +199,7 @@ You could extend the validation in `ValidateMessage` in similar ways to `Validat
 
 In C# modules, you can register for `Connect` and `Disconnect` events by using a special `ReducerKind`. We'll use the `Connect` event to create a `User` record for the client if it doesn't yet exist, and to set its online status.
 
-We'll use `User.FilterByIdentity` to look up a `User` row for `dbEvent.Sender`, if one exists. If we find one, we'll use `User.UpdateByIdentity` to overwrite it with a row that has `Online: true`. If not, we'll use `User.Insert` to insert a new row for our new user. All three of these methods are generated by the `[SpacetimeDB.Table]` attribute, with rows and behavior based on the row attributes. `FilterByIdentity` returns a nullable `User`, because the unique constraint from the `[SpacetimeDB.Column(ColumnAttrs.PrimaryKey)]` attribute means there will be either zero or one matching rows. `Insert` will throw an exception if the insert violates this constraint; if we want to overwrite a `User` row, we need to do so explicitly using `UpdateByIdentity`.
+We'll use `User.FindByIdentity` to look up a `User` row for `dbEvent.Sender`, if one exists. If we find one, we'll use `User.UpdateByIdentity` to overwrite it with a row that has `Online: true`. If not, we'll use `User.Insert` to insert a new row for our new user. All three of these methods are generated by the `[SpacetimeDB.Table]` attribute, with rows and behavior based on the row attributes. `FilterByIdentity` returns a nullable `User`, because the unique constraint from the `[SpacetimeDB.Column(ColumnAttrs.PrimaryKey)]` attribute means there will be either zero or one matching rows. `Insert` will throw an exception if the insert violates this constraint; if we want to overwrite a `User` row, we need to do so explicitly using `UpdateByIdentity`.
 
 In `server/Lib.cs`, add the definition of the connect reducer to the `Module` class: