Update gdextension_cpp_example.rst to avoid unquoted compatibility_minimum trap

[dashdotdashdot]

Fixes #7864 - demonstrates to reader that compatibility_minimum is better enclosed in quotes (to avoid a misleading error from parsing unquoted three-element version numbers e.g. 4.1.1).

• Bugsquad edit, fixes: .gdextension is not loading if compatibility_minimum mentions patch version godot#80590

[AThousandShips]

Can confirm that with quotes the underlying parsing in ConfigFile does give the correct results

[dsnopek]

Thanks!

[capnm]

While you're at it, you could here also fix the wrong [Icon] comments...
See godotengine/godot#75472 :

...

[icons]
GDExample = "res://icons/icon_gdexample.svg"

[AThousandShips]

It is fixed, you're out of date

Edit: My bad, got it backward

This is already handled in, so shouldn't be done here:

• Custom editor icon section's command wrong or out of date #7820

[mhilbrunner]

Good call. Thanks and congrats on your first merged contribution to Godot's docs!

[mhilbrunner]

Cherry-picked to 4.1