Add URL to license #4

Job	Run time
build_font / Build main TTFs	2m 31s
build_font / Regression test	1m 18s
build_font / Create proof documents	2m 42s
build_font / Check with fontspector	56s
build_font / Submit PR to Google Fonts	0s
build_font / Create release	-1s
build_font / Rebuild website	1m 26s
build_font / Deploy website to GitHub Pages	20s
	9m 12s

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