Added spelling option to make.bat.

docs/make.bat

@@ -34,6 +34,7 @@ if "%1" == "help" (
 	echo.  changes    to make an overview over all changed/added/deprecated items
 	echo.  linkcheck  to check all external links for integrity
 	echo.  doctest    to run all doctests embedded in the documentation if enabled
+	echo.  spelling   to check for typos in documentation
 	goto end
 )
 
@@ -186,4 +187,13 @@ results in %BUILDDIR%/doctest/output.txt.
 	goto end
 )
 
+if "%1" == "spelling" (
+	%SPHINXBUILD% -b spelling %ALLSPHINXOPTS% %BUILDDIR%/spelling
+	if errorlevel 1 exit /b 1
+	echo.
+	echo.Check finished. Wrong words can be found in %BUILDDIR%/^
+spelling/output.txt.
+	goto end
+)
+
 :end