Project - Move requirements

Use kind of **requirements.txt** file to list and gather Python dependencies (names and versions) and update documentation to run cmmand lile:

```shell
pip install -m requirements.txt
```

where such file contains stuff like (here _foo_, _bar_ and _wizz_ are dependencies):

```text
foo==1.2.3
bar==4.5.6
wizz==7.8.9
```

And update doctor script.