add readme for each directory

misc/README.md

@@ -0,0 +1,21 @@
+# Miscellaneous
+
+These files contain important data sourced by the configuration, or simply
+information to store for safekeeping later.
+
+---
+
+Creating hashed password for [password.sha512](./password.sha512):
+
+```
+mkpasswd -m sha-512
+```
+
+---
+
+Getting key for [public-keys](./public-keys):
+
+```
+ssh-keyscan -t ed25519 <hostname>
+```
+