README.md: update for Go module-based build

Change-Id: I16fb74da240d97cc4d13fa2fadd57bcdcb48f2f5
Reviewed-on: https://go-review.googlesource.com/c/perf/+/355469
Trust: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
diff --git a/README.md b/README.md
index 4691e5b..6ddc655 100644
--- a/README.md
+++ b/README.md
@@ -21,8 +21,8 @@
 the complete stack on your machine with an in-memory datastore.
 
 ```
-go get -u golang.org/x/perf/storage/localperfdata
-go get -u golang.org/x/perf/analysis/localperf
+go install golang.org/x/perf/storage/localperfdata@latest
+go install golang.org/x/perf/analysis/localperf@latest
 localperfdata -addr=:8081 -view_url_base=http://localhost:8080/search?q=upload: &
 localperf -addr=:8080 -storage=http://localhost:8081
 ```
@@ -34,8 +34,9 @@
 
 ## Download/Install
 
-The easiest way to install is to run `go get golang.org/x/perf/cmd/...`.
-You can also manually git clone the repository and run `go install ./cmd/...`.
+The easiest way to install is to run `go install
+golang.org/x/perf/cmd/...@latest`. You can also manually git clone the
+repository and run `go install golang.org/x/perf/cmd/...`.
 
 ## Report Issues / Send Patches