Update description of rule (#74)

Author: sdwheeler

reference/docs-conceptual/PSScriptAnalyzer/Rules/UseDeclaredVarsMoreThanAssignments.md

@@ -1,7 +1,7 @@
 ---
 description: Extra Variables
-ms.custom: PSSA v1.20.0
-ms.date: 10/18/2021
+ms.custom: PSSA v1.21.0
+ms.date: 06/30/2022
 ms.topic: reference
 title: UseDeclaredVarsMoreThanAssignments
 ---
@@ -11,8 +11,11 @@ title: UseDeclaredVarsMoreThanAssignments
 
 ## Description
 
-Generally variables that are not used more than their assignments are considered wasteful and not
-needed.
+Variables that are assigned but not used are not needed.
+
+> [!NOTE]
+> For this rule, the variable must be used within the same scriptblock that it was declared or it
+> won't be considered to be "used".
 
 ## How
 
@@ -40,3 +43,20 @@ function Test
     Write-Output $declaredVar
 }
 ```
+
+### Special case
+
+The following example triggers the **PSUseDeclaredVarsMoreThanAssignments** warning because `$bar`
+is not used within the scriptblock where it was defined.
+
+```powershell
+$foo | ForEach-Object {
+    if ($_ -eq $false) {
+        $bar = $true
+    }
+}
+
+if($bar){
+    Write-Host 'Collection contained a false case.'
+}
+```