add new codeMeta diagram

[lindangulopez]

Update crosswalk diagram to svg

[progval]

that's a PNG file, not SVG. Though I just realized you made it from a webpage (https://codepen.io/lindangulopez/pen/pvEvwMO) so there isn't an easy way to convert to SVG.

I'll see with @meldra if there is a way to make this a SVG. Otherwise we'll keep the PNG (though this PR will need to remove the old SVG and point to the PNG instead, because currently the new PNG is not visible)

[lindangulopez]

I updated this with a .svg.

[meldra]

Linda, if you did, it is not pushed.

The file in the currently visible version of the PR has a .png extension

And the mime-type of the image in this PR when checked out locally is image/png:

$ file --mime-type codeMeta_crosswalk_diagram.png
codeMeta_crosswalk_diagram.png: image/png

[progval]

@lindangulopez you pushed it in the codeMeta-diagram branch (https://github.com/lindangulopez/codemeta.github.io/blob/codeMeta-diagram/static/img/crosswalkdiagram.svg), but this PR was opened from the master branch

[meldra]

I suspect that svg is going to be too big on the page.

[lindangulopez]

feel free to adjust <svg width="1200" height="550" viewBox="0 0 1200 550" xmlns="http://www.w3.org/2000/svg">