docs: update howto-tests.txt

Signed-off-by: Karel Zak <kzak@redhat.com>

Documentation/howto-tests.txt

@@ -5,21 +5,25 @@
  It's expected that for each invasive change or important bugfix you will
  include a test to your patch.
 
- Compile tests & run basic tests:
+ Compile binaries, libs, extra test programs and run the basic tests:
 
 	$ make check
 
+ Compile extra test programs only:
+
+	$ make check-programs
+
  Note that the configure option --disable-static disables many of libmount and
  libblkid unit tests.
 
  Run all tests including tests that require root permissions:
 
 	# cd tests
-	# ./run.sh [--verbose] [--memcheck]
+	# ./run.sh [options, see --help]
 
 	Alternatively using sudo and make:
 
-	$ make check TS_COMMAND="true"
+	$ make check-programs
 	$ sudo -E make check TS_OPTS="--parallel=1"
 
  note that as root you have to manually remove output and diff directories
@@ -31,6 +35,7 @@
 
  Run subset of tests:
 
+	$ cd tests
 	$ ./run.sh <test_directory-name>
 
         for example:
@@ -38,6 +43,10 @@
               $ ./run.sh blkid
               $ ./run.sh libmount
 
+        or individual test script, for example:
+
+	      $ ./ts/cal/year
+
  The tests is possible to exclude by ./run.sh --exclude=<list>  where the
  <list> is blank separated test names in format "testdir/testname", for example: