Add sops and setup sops-nix

We want to store secrets, and due to the shortcomings of git-crypt (not
working, not being able to push to public caches, etc.) we have decided
to use sops.

Change-Id: I9ed38a93879ca5ff4a452e6e8017b500a4d2cbb6
Reviewed-on: https://git.clicks.codes/c/Chimera/NixFiles/+/414
Tested-by: Skyler Grey <minion@clicks.codes>
Reviewed-by: Skyler Grey <minion@clicks.codes>
diff --git a/.gitignore b/.gitignore
index 0e2b511..7e7e5f0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,5 @@
 tmp/
 
 result/
+
+.sops.yaml
\ No newline at end of file