Add tags for ECP applications that are in Spack.

- All now have both 'ecp' and 'ecp-apps' tags.
- ECP ST projects will eventually also have ecp and ecp-software tags.

var/spack/repos/builtin/packages/nek5000/package.py

@@ -45,7 +45,7 @@ class Nek5000(Package):
     url      = "https://github.com/Nek5000/Nek5000"
 
     tags = ['cfd', 'flow', 'hpc', 'solver', 'navier-stokes',
-            'spectral-elements', 'fluid']
+            'spectral-elements', 'fluid', 'ecp', 'ecp-apps']
 
     version('17.0', '6a13bfad2ce023897010dd88f54a0a87',
             url="https://github.com/Nek5000/Nek5000/releases/download/"