Add docs to internal functions #640

Job	Run time
Julia 1 - ubuntu-latest - x64 - pull_request	24m 42s
Julia 1.6 - ubuntu-latest - x86 - pull_request	24m 38s
Julia 1.6 - ubuntu-latest - x64 - pull_request	18m 45s
benchmark (run_benchmarks_pmedian.jl)	2m 30s
benchmark (run_benchmarks.jl)	7m 25s
benchmark (run_benders_quantile_regression_benchmark.jl)	2m 36s
benchmark (run_benchmarks_jump.jl)	7m 53s
	1h 28m 29s

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