document the recognized extensions

[jerabaul29]

From the user manual https://lucianopaz.github.io/compress_pickle/html/ :

>>> fname2 = "gzip_compressed_data.gz"  # The compression is inferred from the extension
>>> dump(obj, fname2)

Can you document there which extensions are recognized? Which extensions can I use to automatically use lzma for example?

[lucianopaz]

You can find the list of registered extensions by calling:

from compress_pickle.compressers.registry import get_registered_extensions

get_registered_extensions()

I'll explicitly write that down in the documentation. The information is in the API docs but it's harder to find.