readme: update section about installation

Go 1.3 mentioned in installation section was EOLed many years ago. No
sense to describe it's installation. Go 1.3 replaced with Go 1.13. Go
1.13 is outdated too and unsupported, but we run tests with it in Github
Actions so it is a guarantee that everything will works with it.

Author: ligurio

README.md

@@ -28,21 +28,12 @@ faster than other packages according to public benchmarks.
 
 ## Installation
 
-We assume that you have Tarantool version 1.6 and a modern Linux or BSD
+We assume that you have Tarantool version 1.6+ and a modern Linux or BSD
 operating system.
 
-You will need a current version of `go`, version 1.3 or later (use
-`go version` to check the version number). Do not use `gccgo-go`.
-
-**Note:** If your `go` version is younger than 1.3, or if `go` is not installed,
-download the latest tarball from [golang.org](https://golang.org/dl/) and say:
-
-```bash
-$ sudo tar -C /usr/local -xzf go1.7.5.linux-amd64.tar.gz
-$ export PATH=$PATH:/usr/local/go/bin
-$ export GOPATH="/usr/local/go/go-tarantool"
-$ sudo chmod -R a+rwx /usr/local/go </pre>
-```
+You will need a current version of `go`, version 1.13 or later (use `go version`
+to check the version number). Do not use `gccgo-go`. Lean more about Go
+installation on [official site](https://go.dev/doc/install).
 
 The `go-tarantool` package is in
 [tarantool/go-tarantool](github.com/tarantool/go-tarantool) repository.