add new rule for Sigma ransomware

from https://securelist.com/energetic-bear-crouching-yeti/85345/

https://www.symantec.com/blogs/threat-intelligence/orangeworm-targets-healthcare-us-europe-asia

Adding all rules from https://www.us-cert.gov/HIDDEN-COBRA-North-Korean-Malicious-Cyber-Activity

from https://securingtomorrow.mcafee.com/mcafee-labs/ransomware-takes-open-source-path-encrypts-gnu-privacy-guard/

https://www.nccgroup.trust/us/about-us/newsroom-and-events/blog/2018/march/apt15-is-alive-and-strong-an-analysis-of-royalcli-and-royaldns/

Rules from https://www.carbonblack.com/2018/02/27/threat-analysis-rokrat-malware/

adding rule from https://blueliv.com/petya-ransomware-cyber-attack-is-spreading-across-the-globe-part-2/

rules from https://blueliv.com/wannacrypt-malware-analysis/

https://www.alienvault.com/blogs/labs-research/a-north-korean-monero-cryptocurrency-miner