Document `uv` installation example.

[alxmrs]

For torch + cuda projects, it seems like the community is centering around managing dependencies with uv. To help users who use all three of these tools, I bet it would be useful to include such documentation in a "how to install" section. To that end, here is how I got this library installed in my project:

According to this comment (astral-sh/uv#1715 (comment)), it seems that earth2grid can be installed with the following two step process:

uv add https://github.com/NVlabs/earth2grid/archive/main.tar.gz
uv sync --no-install-package earth2grid

This should modify the pyproject.toml to have something like the following configuration (it may require manual modification):

# ...
dependencies = [
    # ...
    "earth2grid",
]
# ...
[tool.uv.sources]
earth2grid = { url = "https://github.com/NVlabs/earth2grid/archive/main.tar.gz" }

[tool.uv]
no-build-isolation-package = ["earth2grid"]

This should ensure that earth2grid is installed correctly in uv-managed projects.

(see https://docs.astral.sh/uv/reference/settings/#no-build-isolation-package)

[alxmrs]

On a related note: is it possible to simply install the project from a git address? For example:

uv add https://github.com/NVlabs/earth2grid.git  
uv sync --no-install-package earth2grid

[alxmrs]

Furthermore, it's uncertain to me if the above method is the best way to install this dependency, or this other approach that is common to use for flash-attn:

astral-sh/uv#6437 (comment)