Update plugins.md (#7038)
Update plugins.md (#7038)

Added proposed 3rd party integration: WP-Trip-Summary WordPress plug-in that uses LeafletJS as a mapping component.
Leaflet/Leaflet,CapeSepias/Leaflet,Leaflet/Leaflet,Leaflet/Leaflet,CapeSepias/Leaflet,CapeSepias/Leaflet