[doc][core][ndarray] Update Doctoring format & errors for NDArray

[shivasankarka]

1. This PR standardizes the Doctoring format according to Mojo docstring style guide (and to be aligned with numpy) which is as follows,

Description:
Parameters:
Args:
Returns:
Raises:
See Also:
Notes:
References
Examples:

2. Add more descriptive errors in the internal functions of NDArray to give better understanding of the errors and also their source.

[forfudan]

@shivasankarka It is also related to Mojo docstring style guide. The guide is consistent with numpy.

[forfudan]

De-indent the examples block according to the mojo style guide.

Otherwise, the hinter will render them in as one line.

[forfudan]

Approved with some adjustment and reverts.