Adding documentation for typical usages of OpenFAST #2287

Job	Run time
build-all-debug	6m 31s
build-postlib-release	14m 43s
build-drivers-release	4m 49s
build-test-uadriver-debug	2m 41s
build-all-debug-single	3m 21s
rtest-module-drivers	2m 46s
rtest-modules-debug	5m 3s
build-interfaces-release	3m 54s
build-fastfarm-release	10m 6s
build-openfast-release	3m 2s
rtest-OF-simulink	9m 43s
rtest-OF	7m 15s
rtest-OF-5MW_Land_AeroMap	1m 8s
rtest-OF-5MW_OC3Mnpl_DLL_WTurb_WavesIrr	1m 46s
rtest-OF-5MW_OC4Jckt_DLL_WTurb_WavesIrr_MGrowth	1m 13s
rtest-OF-5MW_OC4Semi_WSt_WavesWN	1m 37s
rtest-OF-5MW_Land_BD_DLL_WTurb	2m 57s
rtest-OF-5MW_OC3Trpd_DLL_WSt_WavesReg	8m 40s
rtest-OF-linearization	2m 37s
rtest-interfaces	4m 56s
rtest-FF	1m 57s
	1h 40m 45s

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