Suggesting documentation improvements/enhancements

[tgkolda]

In the documentation of the tensor classes, I noticed that there are a few things that might be enhanced.

1. For every tensor class, it says the name in all caps and then explains what it is. This is presumably leftover for porting the MATLAB documentation, where the all caps was a special indicator. I suggest to remove this in all the classes. For example, the dense tensor class help has TENSOR Class for dense tensors. and I suggest to change it to just Class for dense tensors.

2. The __init()__ function is not linking in the help documentation. I'm not sure what the fix is here, but it's confusing. Maybe change

Instances of :class:`pyttb.tensor` can be created using `__init__()` or
    the following method:

      * :meth:`from_function`

to

Instances of :class:`pyttb.tensor` can be created as in the examples below or
    via the following method:

      * :meth:`from_function`

3. The examples do not illustrate all the inputs. For example, in tensor there is no illustration of using shape or copy.

4. Should creating a tensor as via eq or copy also be mentioned as ways to create a tensor?

I am specify to tensor, but these happen in all the tensor classes: tensor, sptensor, ktensor, etc.