Update README.md

Author: BenjaminMichaelis

README.md

@@ -45,12 +45,13 @@ To find potentially mismatched listings in a chapter run,
 will be printed to the console.
 
 To run all chapters in powershell from ListingManager directory,
+```
 Get-ChildItem -Path 'insert.srcPathNameHere' -Directory | Where-Object {
 !$_.name.EndsWith("Tests")
 } | ForEach-Object {
 listingmanager --path $_.FullName --preview --verbose
 } 
-
+```
 
 # Pushing new versions