mod/ssh-keys-import: make ssh-keys-import a module

doc/mod/ssh-keys-import.md

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+Import ssh keys for public key authentication
+=============================================
+
+[⬅️ Go back to main README](../../README.md)
+
+![required RouterOS version](https://img.shields.io/badge/RouterOS-7.9beta4-yellow?style=flat)
+
+> ℹ️️ **Info**: This module can not be used on its own but requires the base
+> installation. See [main README](../../README.md) for details.
+
+Description
+-----------
+
+RouterOS supports ssh login with public key authentication. The functions
+in this module help importing the keys.
+
+Requirements and installation
+-----------------------------
+
+Just install the module:
+
+    $ScriptInstallUpdate mod/ssh-keys-import;
+
+Usage and invocation
+--------------------
+
+### Import single key from terminal
+
+Call the function `$SSHKeysImport` with key and user as parameter to
+import that key:
+
+    $SSHKeysImport "ssh-rsa ssh-rsa AAAAB3Nza...QYZk8= user" admin;
+
+The third part of the key (`user` in this example) is inherited as
+`key-owner` in RouterOS.
+
+### Import several keys from file
+
+The functions `$SSHKeysImportFile` can read an `authorized_keys`-style file
+and import all the keys. The user given to the function can be overwritting
+from comments in the file. Create a file `keys.pub` with this content:
+
+```
+ssh-rsa AAAAB3Nza...QYZk8= user@client
+ssh-rsa AAAAB3Nza...ozyts= worker@station
+# user=example
+ssh-rsa AAAAB3Nza...GXQVk= person@host
+```
+
+Then import it with:
+
+    $SSHKeysImportFile keys.pub admin;
+
+This will import the first two keys for user `admin` (as given to function)
+and the third one for user `example` (as defined in comment).
+
+---
+[⬅️ Go back to main README](../../README.md)  
+[⬆️ Go back to top](#top)