Add an article explaining how to install `protoc` #89

Job	Run time
Soundness / Check generated code	1m 16s
Soundness / Swift license headers check	2s
Unit tests / Construct unit test matrix	5s
Cxx interop / Construct Cxx interop matrix	3s
Soundness / API breakage check	2m 0s
Soundness / Documentation check	1m 18s
Soundness / Broken symlinks check	4s
Soundness / Format check	36s
Soundness / License headers check	5s
Soundness / Python lint check	7s
Soundness / Shell check	30s
Soundness / Unacceptable language check	4s
Soundness / YAML lint check	4s
Cxx interop / Cxx interop / Linux (6.0)	1m 17s
Cxx interop / Cxx interop / Linux (nightly-6.1)	1m 21s
Cxx interop / Cxx interop / Linux (nightly-main)	1m 20s
Unit tests / Unit tests / Linux (6.0)	1m 28s
Unit tests / Unit tests / Linux (nightly-6.1)	1m 54s
Unit tests / Unit tests / Linux (nightly-main)	1m 40s
	15m 14s

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