Add a "Trouble shooting" section to the plugins.

Add a "Trouble shooting" section to the README file and point to it from the issue template. Entries should include:

- Check if configuration is correct (Info.plist on iOS and AndroidManifest.xml on Android).
- Make sure emulator is configured correctly (see instruction mentioned here: https://github.com/Baseflow/flutter-geolocator/issues/1082#issuecomment-1160457180).
- Reset cache / restart emulator.
- Test on real device if possible.

Read the repository README and issue template first to find the appropriate sections and wording style. Add the requested troubleshooting checks and link to the section from the issue template; done means all four entries and the link are present and render correctly.

Written by the indexing model from the issue text.