docs: add note about binary requirement for plugin (golangci#3468)

Author: philiplinell

Diff for: docs/src/docs/contributing/new-linters.mdx

@@ -41,6 +41,11 @@ Some people and organizations may choose to have custom-made linters run as a pa
 Typically, these linters can't be open-sourced or too specific.
 Such linters can be added through Go's plugin library.
 
+For a private linter (which acts as a plugin) to work properly,
+the plugin as well as the golangci-lint binary needs to be built for the same environment. `CGO_ENABLED` is another requirement.
+This means that `golangci-lint` needs to be built for whatever machine you intend to run it on
+(cloning the golangci-lint repository and running a `CGO_ENABLED=1 make build` should do the trick for your machine).
+
 ### Configure a Plugin
 
 If you already have a linter plugin available, you can follow these steps to define it's usage in a projects