DOC: lib/shape_base numpydoc formatting.

[Carreau]

Numpydoc parses parameter different depending on whether there is a space
before the colon, for it to be properly interpreted as names and types;
spaces need to be put on each side.

[mattip]

I don't see a difference in the rendered documents before and after. Am I missing something?

[Carreau]

Space before the colon, italic for ndarray. Hard to see for this theme, but could be more proeminent in other.

It's not about the style, it's about the semantic, and it prevent a terminal render I'm working on in IPython to detect that the documented parameters are arr and indices.

wile a properly spaced items will be detected correctly by numpydoc (here np.where), see how condition, x and y are green so correctly infered.

[mattip]

Thanks @Carreau