infra/go: Adding setup instructions and quick setup script.

go/README.md

 # Chromium Infra Go Area
 
 [TOC]
 
+
+## Get the code
+
+The steps for getting the code are:
+
+ 1. [Install depot_tools](https://www.chromium.org/developers/how-tos/install-depot-tools)
+ 1. Run `fetch infra`
+ 1. Run `infra/go/env.py`
+
+
+### Quick Setup
+
+If you are on Linux you can run the [quicksetup script](quicksetup.sh) like so:
+
+```shell
+cd /where/you/want/source/code
+wget -O- "https://chromium.googlesource.com/infra/infra/+/master/go/quicksetup.sh?format=TEXT" | base64 -d | bash
+```
+
+This will create a self-contained `cr-infra-go-area` directory and populate it
+will all necessary tools and source for using or contributing to Chromium's Go
+Infrastructure. Once run, look in `cr-infra-go-area/infra/go/src` for the
+editable source code.
+
+
 ## Structure
 
 This directory contains a set of scripts to setup and manage a hermetic Go
 building environment. We pin versions of the Go toolset and all third party
 dependencies that the infra code is using. It is important for getting
 non-flaky, reproducible builds of Go code on a CI and on developers' machines.
 
 Structurally `infra/go` represents two workspaces (two directories in
 `$GOPATH`):
 
@@ skipping 14 matching lines @@
 [luci-go](https://github.com/luci/luci-go) project that **is** a proper Go
 package and can be fetched with `go get`.
 
 luci-go doesn't pin any dependencies, assuming the end users (whoever links to
 it) will do it themselves. `infra/go` workspace is one such end user. This
 approach allows projects that use multiple big libraries (like luci-go) to
 manage all dependencies centrally in a single place, thus avoiding issues of
 version conflicts and binary bloat due to inclusion of a same third party code
 via multiple import paths.
 
+
 ## Bootstrap
 
 `infra/go` knows how to bootstrap itself from scratch (i.e. from a fresh
 checkout) by downloading pinned version of Go toolset, and installing pinned
 versions of third party packages it needs into `infra/go/.vendor` directory, and
 adding a bunch of third party tools (like `goconvey` and `protoc-gen-go`) to
 `$PATH`.
 
 The bootstrap (and self-update) procedure is invoked whenever `go/bootstrap.py`
 or `go/env.py` run. There's **no** DEPS hook for this. We only want the Go
@@ skipping 98 matching lines @@
 Some Golang related packages are already on `*.googlesource.com` (though it may
 be non obvious at the first glance). For example all `golang.org/x/*` ones are
 actually served from `https://go.googlesource.com/`.
 
 `deps.py` will warn you if it sees a package being referenced from
 a source-of-truth repo, and not a mirror.
 
 If you are positive that a mirror is needed, file
 [Infra-Git](https://bugs.chromium.org/p/chromium/issues/entry?template=Infra-Git)
 ticket specifying what repository you need to be mirrored.