[doc][core][ndarray] Update Doctoring format & errors for NDArray (#222)

1) This PR standardizes the Doctoring format according to [Mojo
docstring style
guide](https://github.com/modular/mojo/blob/main/stdlib/docs/docstring-style-guide.md)
(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.

---------

Co-authored-by: ZHU Yuhao 朱宇浩 <dr.yuhao.zhu@outlook.com>

Author: shivasankarka