Updating README with clearer build instructions (#3550)

Author: StevenBucher98

README.md

@@ -240,6 +240,9 @@ The build script `build.ps1` can be used to bootstrap, build and test the projec
     * Targeting .NET Core: `./build.ps1 -Test -Configuration Debug -Framework netcoreapp2.1`
 
 After build, the produced artifacts can be found at `<your-local-repo-root>/bin/Debug`.
+In order to isolate your imported module to the one locally built, be sure to run 
+`pwsh -NonInteractive -NoProfile` to not automatically load the default PSReadLine module installed.
+Then, load the locally built PSReadLine module by `Import-Module <your-local-repo-root>/bin/Debug/PSReadLine/PSReadLine.psd1`.
 
 [Contribution Guide]: https://github.com/PowerShell/PSReadLine/blob/master/.github/CONTRIBUTING.md