Move Fortran section of user guide to the top level #1176

Job	Run time
docs_install_guide_pdf	5m 48s
docs_package_pdf (cvode)	8m 42s
docs_package_pdf (idas)	9m 8s
docs_package_pdf (cvodes)	8m 6s
docs_package_pdf (kinsol)	9m 43s
docs_package_pdf (arkode)	10m 5s
docs_examples_sphinx_pdf (kinsol)	3m 22s
docs_package_pdf (ida)	8m 55s
docs_examples_latex_pdf (cvodes)	2m 56s
docs_examples_latex_pdf (cvode)	3m 21s
docs_examples_sphinx_pdf (arkode)	1m 51s
docs_examples_latex_pdf (idas)	1m 32s
docs_examples_latex_pdf (ida)	1m 32s
	1h 15m 1s

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