add instructions for FreeBSD

doc/INSTALL.md

@@ -42,6 +42,51 @@ Docker is used to build Alpine Linux
 ### Build docker image
 
 ## FreeBSD
-### Package install
+
+FreeBSD has ports for both cligen and clixon available.
+You can install them as binary packages, or you can build
+them in a ports source tree locally.
+
+If you install using binary packages or build from the
+ports collection, the installation locations comply
+with FreeBSD standards and you have some assurance
+that the installed package is correct and functional.
+
+The nginx setup for RESTCONF is altered - the system user
+www is used, and the restconf daemon is placed in
+/usr/local/sbin.
+
+### Binary package install
+
+To install the pre-built binary package, use the FreeBSD
+pkg command.
+
+```
+% pkg install clixon
+```
+
+This will install clixon and all the dependencies needed.
+
 ### Build from source
 
+If you prefer you can also build clixon from the
+[FreeBSD ports collection](https://www.freebsd.org/doc/handbook/ports-using.html)
+
+Once you have the Ports Collection installed, you build
+clixon like this:
+
+```
+% cd /usr/ports/devel/clixon
+% make && make install
+```
+
+One issue with using the Ports Collection is that it may
+not install the latest version from GitHub. The port is
+generally updated soon after an official release, but there
+is still a lag between it and the master branch. The maintainer
+for the port tries to assure that the master branch will
+compile always, but no FreeBSD specific functional testing
+is done.
+
+
+