Speedup sphinx-build using parallelization
Distribute sphinx-build over several processes in parallel
to make building on multiprocessor machines faster.
Using 'auto' which equals the number of CPUs available.
See docs at
* Move `-j auto` to SPHINXOPTS
# Makefile for Sphinx documentation
# You can set these variables from the command line.
-SPHINXOPTS =
+SPHINXOPTS = -j auto
SPHINXBUILD = sphinx-build
SPHINXAUTOGEN = sphinx-autogen
BUILDDIR = _build
