naming: rename minimal -> tiny

This renames the minimal profile to "tiny", it's useful to have a
profile that builds quickly and provides a small artifact. However, the
minimal name mirrors the Fedora Minimal spin name and might confuse
people building images about what they're actually building.

The Tiny descriptions do not replicate the Fedora Minimal spin.

Signed-off-by: Simon de Vlieger <supakeen@redhat.com>

tmt/plans/base/tiny-disk.xml

@@ -1,9 +1,9 @@
-summary: Build Minimal disk image
+summary: Build Tiny disk image
 discover:
     how: fmf
 environment:
     image_type: oem
-    image_profile: Minimal-Disk
+    image_profile: Tiny-Disk
     kiwi_file: Fedora.kiwi
 execute:
     how: tmt