Add new doc to introduce how to create case file

casefile is used to save what test cases will be used finally. So
a proper introduction is necessary.

BTW, fix a spell mistake in runmcetest.

Signed-off-by: Chen, Gong <gong.chen@linux.intel.com>
diff --git a/doc/casefile-howto.txt b/doc/casefile-howto.txt
new file mode 100644
index 0000000..da3b2e4
--- /dev/null
+++ b/doc/casefile-howto.txt
@@ -0,0 +1,8 @@
+casefile is used to save what test cases will be used finally. Here is an
+example to create it by hand.
+
+1. Copy one or more files from directory groups, say function, to somewhere.
+2. Open this file and remove all "on|off" at the end of line from every line.
+3. Delete unnecessary test cases. Here one line corresponds to one test case.
+4. Save this file and rename it to any name you prefer.
+5. When you execute runmcetest, use parameter "-l" along with this file.
diff --git a/runmcetest b/runmcetest
index 8bf9554..8e95f15 100755
--- a/runmcetest
+++ b/runmcetest
@@ -193,12 +193,12 @@
 	cat <<-EOF
 
 	usage: ${0##*/} [ -t TMPDIR ] [ -s SUMFILE ] [ -o OUTDIR ]
-	[ -b TOODIR ] [ -l CASEFILE ] [ -r RUNTIMES ]
+	[ -b TOOLDIR ] [ -l CASEFILE ] [ -r RUNTIMES ]
 
 	-t TMPDIR       Directory where temporary files will be created. Don't use important directory.
 	-s SUMDIR       Directory where summary files will be created.
 	-o OUTDIR       Directory where raw test outputs will be created.
-	-b TOODIR	Directory where tool utilities will be placed.
+	-b TOOLDIR	Directory where tool utilities will be placed.
 	-l CASEFILE     File where test case list will be used in the test.
 	-r RUNTIMES	Assign the whole test rounds. 0 means infinite loop.
 	-h              Help. Prints all available options.