maint: Move examples from 'tests' to 'examples' directory.

* examples/gnu-system.scm: Moved from 'tests' directory.
* examples/guix-jobs.scm: Likewise.
* examples/guix-track-git.scm: Likewise.
* examples/hello-git.scm: Likewise.
* examples/hello-singleton.scm: Likewise.
* examples/hello-subset.scm: Likewise.
* Makefile.am (EXTRA_DIST): Adapt.
* README <Example>: Likewise.

Makefile.am

@@ -113,10 +113,10 @@ EXTRA_DIST = \
   bin/evaluate.in \
   bootstrap \
   src/cuirass/config.scm.in \
-  tests/gnu-system.scm \
-  tests/guix-jobs.scm \
-  tests/hello-singleton.scm \
-  tests/hello-subset.scm \
+  examples/gnu-system.scm \
+  examples/guix-jobs.scm \
+  examples/hello-singleton.scm \
+  examples/hello-subset.scm \
   $(TESTS)
 
 MOSTLYCLEANFILES = $(bin_SCRIPTS) src/cuirass/config.scm

README

@@ -26,9 +26,9 @@ Example
 
 A quick way to manually test Cuirass is to execute:
 
-  ./pre-inst-env cuirass --specifications=tests/hello-singleton.scm --database=test.db
+  ./pre-inst-env cuirass --specifications=examples/hello-singleton.scm --database=test.db
 
-This will read the file "tests/hello-singleton.scm" which contains a list of
+This will read the file "examples/hello-singleton.scm" which contains a list of
 specifications and add them to the database "test.db" which is created if it
 doesn't already exist.