added notes

howto - missing or expired repo keys.md

@@ -0,0 +1,14 @@
+# Ubuntu - Missing/expired Repo keys
+
+Find and remove expired key
+
+```shell
+sudo apt-key list
+sudo apt-key del <key> # last 8 characters of hash
+```
+
+Install latest key (i.e.)
+
+```shell
+curl -O https://packages.cloud.google.com/apt/doc/apt-key.gpg && sudo apt-key add apt-key.gpg
+```