Fix the 'html-noplot' make target for docs

[seisman]

make html-noplot started to fail after #3761.

$ make html-noplot

Generating rst source files of API documentation.

sphinx-autogen -i -t _templates -o api/generated api/*.rst
[autosummary] generating autosummary for: api/index.rst
[autosummary] writing to api/generated

Building HTML files without example plots.

sphinx-build -D plot_gallery=0 -M html -j auto "." "_build" -j auto
usage: sphinx-build [OPTIONS] SOURCEDIR OUTPUTDIR [FILENAMES...]
sphinx-build: error: unrecognized arguments: -M
make: *** [Makefile:42: html-noplot] Error 2

In sphinx-build make-mode, -M must be the first option flag, then the source directory and build directory. All other options should be put at the end.

This PR patches #3761.