Merge branch 'guix' into 'master'

add guix install instructions

See merge request cppit/jucipp!399

docs/install.md

@@ -7,6 +7,7 @@
         - [Fedora](#fedora)
         - [Mageia](#mageia)
         - [OpenSUSE Tumbleweed](#opensuse-tumbleweed)
+        - [GNU Guix/GuixSD](#gnu-guixguixsd)
     - [FreeBSD](#freebsd)
     - MacOS
         - [Homebrew](#macos-with-homebrew-httpbrewsh)
@@ -105,6 +106,12 @@ make
 sudo make install
 ```
 
+## GNU Guix/GuixSD
+Get the juCi++ package definition
+```sh
+guix install jucipp
+```
+
 ## FreeBSD
 On FreeBSD, latest release of juCi++ is available through the port: jucipp.