Merge branch '229-krb5-new-pmodule-for-mit-kerberos5' into 'master'

Resolve "krb5: new Pmodule for MIT Kerberos5"

Closes #229

See merge request Pmodules/buildblocks!334

Tools/krb5/files/variants.yaml

@@ -1,3 +1,4 @@
 overlay: base
 krb5/1.20:
-- relstage: unstable
+- systems: rhel7,rhel8
+  relstage: stable

Tools/krb5/modulefile

@@ -1,18 +1,13 @@
 #%Pmodule
 
-module-whatis		"portable command-line driven graphing utility"
-module-url		"http://www.gnuplot.info/"
-module-license		"See \$GNUPLOT_DIR/share/doc/gnuplot/Copyright"
+module-whatis		"MIT Kerberos5"
+module-url		"https://www.kerberos.org"
+module-license		"MIT"
 module-maintainer	"Achim Gsell <achim.gsell@psi.ch>"
 
 module-help		"
-Gnuplot is a portable command-line driven graphing utility for Linux,
-OS/2, MS Windows, OSX, VMS, and many other platforms. The source code
-is copyrighted but freely distributed (i.e., you don't have to pay for
-it). It was originally created to allow scientists and students to
-visualize mathematical functions and data interactively, but has grown
-to support many non-interactive uses such as web scripting. It is also
-used as a plotting engine by third-party applications like Octave.
-Gnuplot has been supported and under active development since 1986. 
+Kerberos is a network authentication protocol. It is designed to provide
+strong authentication for client/server applications by using secret-key
+cryptography.
 "