Add info for event args, update naming

Author: iserrato

docs/extensibility/visualstudio.extensibility/project/project-concepts.md

@@ -141,11 +141,11 @@ Actions in your project query determine what modifications are made to the proje
 
 These queries support the monitoring of updates made to query results.
 
-| Term                          | Description                                                             |
-| ----------------------------- | ----------------------------------------------------------------------- |
-| SubscribeAsync                | Represents the operation to subscribe to results from a query.          |
-| TrackUpdatesAsync             | Represents the operation to track changes from a query.                 |
-| Workspace.QueryableSpaceEvent | An event that fires on solution open and close. Provides initial state. |
+| Term                | Description                                                             |
+| ------------------- | ----------------------------------------------------------------------- |
+| SubscribeAsync      | Represents the operation to subscribe to results from a query.          |
+| TrackUpdatesAsync   | Represents the operation to track changes from a query.                 |
+| QueryableSpaceEvent | An event that fires on solution open and close. Provides initial state. |
 
 ## Related content
 

docs/extensibility/visualstudio.extensibility/project/project.md

@@ -700,7 +700,7 @@ private class TrackerObserver : IObserver<IQueryTrackUpdates<IFileSnapshot>>
 
 ## Events to monitor solution open and close
 
-The `QueryableSpaceChanged` event can be subscribed to for monitoring when solutions open and close using a workspace created with a service broker.
+The `QueryableSpaceChanged` event can be subscribed to for monitoring when solutions open and close using a workspace created with a service broker. `ProjectQueryableSpaceChangedEventArgs` contains two fields, `SolutionPath` and `QueryableSpaceVersion`. The string `SolutionPath` is the path the solution that opened or null if a solution closed. The int `QueryableSpaceVersion` increments as solutions are opened or closed.
 
 ```csharp
 private void SubscribeToEvent() 
@@ -712,8 +712,8 @@ private void SubscribeToEvent()
 
 private Task EventCalledAsync(ProjectQueryableSpaceChangedEventArgs e)
 {
-    var solutionPath = e.SolutionPath;
-    var version = e.QueryableSpaceVersion;
+    string? solutionPath = e.SolutionPath;
+    int version = e.QueryableSpaceVersion;
     ...
 }
 ```