buildman: Convert documentation to rST

Convert the buildman documentation to rST format and include it in the
'build' section.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Quentin Schulz <foss+uboot@0leil.net>
diff --git a/tools/buildman/func_test.py b/tools/buildman/func_test.py
index f12e996..b4f3b46 100644
--- a/tools/buildman/func_test.py
+++ b/tools/buildman/func_test.py
@@ -249,7 +249,7 @@
     def testFullHelp(self):
         command.test_result = None
         result = self._RunBuildman('-H')
-        help_file = os.path.join(self._buildman_dir, 'README')
+        help_file = os.path.join(self._buildman_dir, 'README.rst')
         # Remove possible extraneous strings
         extra = '::::::::::::::\n' + help_file + '\n::::::::::::::\n'
         gothelp = result.stdout.replace(extra, '')
@@ -260,7 +260,7 @@
     def testHelp(self):
         command.test_result = None
         result = self._RunBuildman('-h')
-        help_file = os.path.join(self._buildman_dir, 'README')
+        help_file = os.path.join(self._buildman_dir, 'README.rst')
         self.assertTrue(len(result.stdout) > 1000)
         self.assertEqual(0, len(result.stderr))
         self.assertEqual(0, result.return_code)