Upload orography and land sea mask for ukv and global

[tam203]

• [x] Orography uploaded.
• [x] Land sea mask not because 'it's complicated'

[tam203]

TODO:

• [ ] Add some high res PNG images showing the model orthography
• [ ] Add high res image showing the 'grid' of the model

The aim of these is to give users an 'at a glance' idea of the resolution of the data set.

We could also:

• [ ] Provide sample plots of the weather fields, again just to illustrate the data.

@bsherratt do you think you could pick this up?