Here are some resources across a few areas (I'll update as I find more)
The Book of Secret Knowledge - https://github.com/trimstray/the-book-of-secret-knowledge
My CCDC cheatsheet has some blue team goodness I've compiled over two competitions - https://gist.github.com/alexiasa/fba4466849fde5b9ec3dd3cd7d1b3e9f
This is broader than SIEM (more about detections in general) but I found it helpful. - https://dragos.com/media/The_Four_Types%20of_Threat_Detection.pdf
MITRE ATT&CK framework logging cheat sheets - https://github.com/MalwareArchaeology/ATTACK
Analyzing Malicious Documents Cheat Sheet - https://zeltser.com/analyzing-malicious-documents/
The Zoo, a malware zoo project - https://github.com/ytisf/theZoo
PacketTotal malware archive - https://packettotal.com/malware-archive.html