Added I18n strings for RPMFILTER and REBOOT_REQD flags from #1448

[Docteh]

Hi, I was looking at the javascript console for other reasons, and noticed complaints about missing strings.

For RPMFILTER I copied the description from https://github.com/betaflight/betaflight/wiki/Arming-Sequence-&-Safety

[McGiverGim]

To me is ok, but usually I left the ARM_SWITCH in the latest position to use the same order here than in the tab.

[mikeller]

Agree with @McGiverGim, the ordering should be preserved.

[Docteh]

done

Side thought: Is the order of these preserved through the translation service? It might be worthwhile to have a reference to the translation service at the very top.

"translation_service": {
    "message": "Translation collaboration for betaflight-configurator is done on crowdin, not through github"
    "url": "https://crowdin.com/project/betaflight-configurator"
}