Added additional information about ExecutionPolicy to readme

readme.txt

@@ -18,6 +18,9 @@ posh-git requires you to modify/create your Powershell Profile.
  - Put all posh-git files in your C:\Users\<username>\Documents\WindowsPowerShell folder (create it if it doesn't exist)
  - Rename profile.example.ps1 to Microsoft.PowerShell_profile.ps1 
  - If you already have a PowerShell_profile.ps1 you can add the code from profile.example.ps1 to it and it should work fine.
+ - posh-git requires you to set the executionpolicy to remotesigned in order to function. Execute (with admin privileges):
+	Set-ExecutionPolicy RemoteSigned 
+	(More Info on ExecutionPolicy: http://technet.microsoft.com/en-us/library/ee176949.aspx)
 
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