Allow make livehtml to watch for changes in tests/

Signed-off-by: Daniel Lim Wee Soong <weesoong.lim@gmail.com>

docs/Makefile

diff --git a/docs/Makefile b/docs/Makefile
index 2bff6bc..0fc9993 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -7,7 +7,7 @@
 # You can set these variables from the command line.
 SPHINXOPTS      =
 SPHINXBUILD     = [ -e env/bin/activate ] && source env/bin/activate; sphinx-build
-SPHINXAUTOBUILD = [ -e env/bin/activate ] && source env/bin/activate; sphinx-autobuild
+SPHINXAUTOBUILD = [ -e env/bin/activate ] && source env/bin/activate; sphinx-autobuild --watch $(MAKEDIR)../tests
 SPHINXPROJ      = SymbiFlowV2X
 SOURCEDIR       = .
 BUILDDIR        = _build