Fix typos in rules (#1913)

Author: sdwheeler

docs/Rules/AvoidUsingComputerNameHardcoded.md

@@ -45,7 +45,7 @@ Function Invoke-MyCommand ($ComputerName)
 ```powershell
 Function Invoke-MyLocalCommand ()
 {
-    Invoke-Command -Port 343 -ComputerName 'hardcodelocalhostname'
+    Invoke-Command -Port 343 -ComputerName hardcodelocalhostname
 }
 ```
 

docs/Rules/ShouldProcess.md

@@ -62,7 +62,7 @@ function Set-File
         [string]$Content
     )
 
-    if ($PSCmdlet.ShouldProcess($Path, ('Setting content to '{0}'' -f $Content)))
+    if ($PSCmdlet.ShouldProcess($Path, ("Setting content to '{0}'" -f $Content)))
     {
         $Content | Out-File -FilePath $Path
     }