[IMPROVED] Update installation commands (#1745)

1. The info about pre go modules is not relevant anymore, so drop it.
2. Extra slashes are not needed before the version suffix, per https://go.dev/ref/mod#go-install. So make it consistent.

Signed-off-by: Alex Bozhenko <alex@synadia.com>

README.md

@@ -19,25 +19,14 @@ A [Go](http://golang.org) client for the [NATS messaging system](https://nats.io
 ## Installation
 
 ```bash
-# Go client
-go get github.com/nats-io/nats.go/
+# To get the latest released Go client:
+go get github.com/nats-io/nats.go@latest
 
-# Server
-go get github.com/nats-io/nats-server
-```
-
-When using or transitioning to Go modules support:
-
-```bash
-# Go client latest or explicit version
-go get github.com/nats-io/nats.go/@latest
-go get github.com/nats-io/nats.go/@v1.37.0
-
-# For latest NATS Server, add /v2 at the end
-go get github.com/nats-io/nats-server/v2
+# To get a specific version:
+go get github.com/nats-io/nats.go@v1.37.0
 
-# NATS Server v1 is installed otherwise
-# go get github.com/nats-io/nats-server
+# Note that the latest major version for NATS Server is v2:
+go get github.com/nats-io/nats-server/v2@latest
 ```
 
 ## Basic Usage