Add leaflet.photon to Leaflet's plugins page

[Oxalin]

While Photon was mentionned in at least one plugin on the Leaflet's plugins page, the leaflet.photon plugin is not listed. To give better visibility to the plugin, it would be advisable to add it to the page.

[lonvia]

This plugin is more or less unmaintained, so I'd be rather reluctant to promote it. In addition, there is a good chance it will break with leaflet 2.

@yohanboniface Any opinions?

[yohanboniface]

This plugin is more or less unmaintained, so I'd be rather reluctant to promote it.

I don't have a strong opinion on this. I'm doing a minimal job to maintain it as per the use of it in uMap, but not more.

In addition, there is a good chance it will break with leaflet 2.

As for any other plugin, I'm afraid :(