Update installation instruction for Go >= v1.17.0

[SubOptimal]

Description

The installation documentation mention go get as the command to install the executable, which was deprecated with Go v1.17.0 and will lead to an error.

go get: installing executables with 'go get' in module mode is deprecated.
    Use 'go install pkg@version' instead.
    For more information, see https://golang.org/doc/go-get-install-deprecation
    or run 'go help get' or 'go help install'.

Reference issue

Assuming that PR #118 might be implemented, the command to install executables should be amended to go install.

PR #118 should be taken into account as the compilation with Go v.1.12.0 will lead to an error.

# github.com/pion/stun
go/1.12.0/src/github.com/pion/stun/checks.go:36:9: undefined: errors.Is
go/1.12.0/src/github.com/pion/stun/checks.go:49:9: undefined: errors.Is
go/1.12.0/src/github.com/pion/stun/client.go:162:5: undefined: errors.Is
go/1.12.0/src/github.com/pion/stun/client.go:331:31: undefined: errors.Is
go/1.12.0/src/github.com/pion/stun/client.go:339:19: undefined: errors.Is
go/1.12.0/src/github.com/pion/stun/client.go:536:27: undefined: errors.Is

PS: Please let me know if I missed some step for contribution. But the offered link to CONTRIBUTING.md mention to check https://pion.ly/knowledge-base/pion-internals/. That link end with a HTTP 404 error.

[codecov[bot]]

Codecov Report

Base: 98.19% // Head: 98.19% // No change to project coverage :thumbsup:

Coverage data is based on head (61be8a2) compared to base (7e647ef). Patch has no changes to coverable lines.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #119 +/- ## ======================================= Coverage 98.19% 98.19% ======================================= Files 20 20 Lines 1608 1608 ======================================= Hits 1579 1579 Misses 23 23 Partials 6 6 ``` | Flag | Coverage Δ | | |---|---|---| | go | `98.19% <ø> (ø)` | | | wasm | `57.18% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pion#carryforward-flags-in-the-pull-request-comment) to find out more. Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pion). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pion)

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[ashellunts]

Hey @SubOptimal, can you please fix linter issues? You can also find them in .github folder and run locally.

[ashellunts]

@SubOptimal thank you for the contribution!