Update gettingstarted.rst
Update gettingstarted.rst

Updated instructions for creating rule file using Windows PowerShell
pombredanne/yara,cblichmann/yara,cblichmann/yara,cblichmann/yara,hillu/yara,VirusTotal/yara,cblichmann/yara,cblichmann/yara,wxsBSD/yara,hillu/yara,hillu/yara,VirusTotal/yara,pombredanne/yara,VirusTotal/yara,pombredanne/yara,VirusTotal/yara,wxsBSD/yara,hillu/yara,VirusTotal/yara,pombredanne/yara,hillu/yara,wxsBSD/yara,pombredanne/yara,wxsBSD/yara,wxsBSD/yara