Fix comment typo in SwiftCommandState.swift (#8165)

`the manifest file should *not* present` -> `the manifest file should
*not* be present`

---------

Co-authored-by: Paul LeMarquand <[email protected]>

Author: MaxDesiatov

Sources/CoreCommands/SwiftCommandState.swift

@@ -238,9 +238,9 @@ public final class SwiftCommandState {
 
     /// Holds the currently active workspace.
     ///
-    /// It is not initialized in init() because for some of the commands like package init , usage etc,
-    /// workspace is not needed, in-fact it would be an error to ask for the workspace object
-    /// for package init because the Manifest file should *not* present.
+    /// It is not initialized in init() because for some of the commands like `package init`, usage etc,
+    /// a workspace is not needed. In fact it would be an error to ask for the workspace object
+    /// for `package init` because the manifest file should *not* be present.
     private var _workspace: Workspace?
     private var _workspaceDelegate: WorkspaceDelegate?