doc: don't use ETCDCTL_API=3 in dl_build
In the spirit of keeping newb instructions simple, do not specify
ETCDCTL_API=3 since it is redundant.
Note: v3 has been the default since
@@ -52,11 +52,11 @@ $ $GOPATH/bin/etcd
Run the following:
```sh
-$ ETCDCTL_API=3 ./bin/etcdctl put foo bar
+$ ./bin/etcdctl put foo bar
OK
```
-(or `ETCDCTL_API=3 $GOPATH/bin/etcdctl put foo bar` if etcdctl was installed with `go get`)
+(or `$GOPATH/bin/etcdctl put foo bar` if etcdctl was installed with `go get`)
If OK is printed, then etcd is working!
