Adding documentation for typical usages of OpenFAST #2300

Job	Run time
build-all-debug-single	3m 37s
build-drivers-release	5m 13s
build-all-debug	6m 19s
build-postlib-release	10m 47s
build-test-uadriver-debug	2m 27s
rtest-module-drivers	2m 38s
rtest-modules-debug	5m 4s
build-openfast-release	3m 23s
build-interfaces-release	3m 25s
build-fastfarm-release	10m 27s
rtest-OF-5MW_Land_AeroMap	1m 16s
rtest-OF	7m 1s
rtest-OF-5MW_OC3Mnpl_DLL_WTurb_WavesIrr	1m 52s
rtest-OF-5MW_Land_BD_DLL_WTurb	2m 17s
rtest-OF-5MW_OC3Trpd_DLL_WSt_WavesReg	4m 36s
rtest-OF-5MW_OC4Jckt_DLL_WTurb_WavesIrr_MGrowth	51s
rtest-OF-5MW_OC4Semi_WSt_WavesWN	1m 32s
rtest-OF-linearization	2m 36s
rtest-OF-simulink	9m 57s
rtest-interfaces	4m 44s
rtest-FF	1m 58s
	1h 32m 0s

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