Add install instructions

Change-Id: Ib1fcd6905f7da426d8e90fae1001f50a3c9d598e
diff --git a/README b/README
index e4eaa20..ec421b7 100644
--- a/README
+++ b/README
@@ -4,3 +4,21 @@
 The main tool of interest is the "presubmitter" command, which
 periodically polls Gerrit for new unverified changes and runs various
 presubmit checks on them.
+Buildglue follows normal Go project conventions, so it can be
+downloaded and installed in just a few steps:
+  # Create a Go workspace (if you don't have one already)
+  mkdir buildglue
+  export GOPATH=$PWD/buildglue
+  # Invoke the go tool
+  go get
+The $GOPATH/src/ directory will now
+contain a clone of the buildglue Git repo, and the $GOPATH/bin
+directory will contain the compiled commands.
+(Caveat: Because currently silently ignores TCP
+connections to port 9418 instead of rejecting them, the "go get"
+command takes longer than necessary to download initially.)