Added installation instructions

README.md

@@ -4,6 +4,23 @@ Keith Irwin ([www.ki9.us](https://www.ki9.us/))
 
 Bash script to update [SSHFP records](https://en.wikipedia.org/wiki/SSHFP_record) using [nsupdate](https://en.wikipedia.org/wiki/Nsupdate).  
 
+## Installation
+
+```sh
+$ sudo su root
+# cd /usr/local/src
+# git clone https://gitea.green.gf4/ki9/nsupdate-sshfp.git
+# ln -s /usr/local/src/nsupdate-sshfp /usr/local/bin/nsupdate-sshfp
+# cp systemd/* /etc/systemd/systemd/
+```
+
+## Upgrade
+
+```sh
+# cd /usr/local/src/nsupdate-sshfp/
+# git pull
+```
+
 ## Usage
 
 ```sh