Leaflet: invalidateSize method docs

[cherniavskii]

Zoom/Pan options in invalidateSize method docs should be clickable (like in setView method docs).
It can be fixed right here.
Feel free to open a PR :)

[IvanSanchez]

This seems to be a trivial uppercase/lowercase problem in the docs. The proper identifier will cause the documentation to create links automatically. See the correct docstrings and compare to the ones that need to be fixed.

And don't forget to read how to build Leaflet documentation.

[LTiger14]

Hey guys, just opened a PR for this issue. The invalidateSize was the only occurrence of this problem I could find. Cheers!