Add installation instructions #776

Job	Run time
Documentation	2m 41s
Julia 1.0 - ubuntu-latest - x64 - pull_request	5m 46s
Julia 1.0 - ubuntu-latest - x86 - pull_request	8m 40s
Julia 1.0 - macOS-latest - x64 - pull_request	7m 23s
Julia 1.0 - windows-latest - x64 - pull_request	11m 0s
Julia 1.0 - windows-latest - x86 - pull_request	13m 28s
Julia 1 - ubuntu-latest - x64 - pull_request	4m 20s
Julia 1 - ubuntu-latest - x86 - pull_request	5m 12s
Julia 1 - macOS-latest - x64 - pull_request	7m 48s
Julia 1 - windows-latest - x64 - pull_request	6m 46s
Julia 1 - windows-latest - x86 - pull_request	9m 52s
Julia nightly - ubuntu-latest - x64 - pull_request	4m 8s
Julia nightly - ubuntu-latest - x86 - pull_request	4m 38s
Julia nightly - macOS-latest - x64 - pull_request	3m 57s
Julia nightly - windows-latest - x64 - pull_request	4m 21s
Julia nightly - windows-latest - x86 - pull_request	5m 14s
	1h 45m 14s

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