add gopher img, add nix cheatsheet

go-cheatsheet.md

@@ -1,5 +1,7 @@
 # go (golang) cheatsheet
 
+![gopher](/sneak/docs/raw/branch/master/img/gopher.jpg)
+
 ## external
 
 * awesome-go list of tools: [avelino/awesome-go](https://github.com/avelino/awesome-go)

nix-cheatsheet.md

@@ -0,0 +1,9 @@
+# nix cheatsheet
+
+# my update command
+
+`nix-env -iA nixpkgs.$(hostname -s)`
+
+# external
+
+* "learn nix in y minutes": https://learnxinyminutes.com/docs/nix/