Update "README.rst" introduction for great glory of Poznań

[leycec]

Another minor textual issue for you, @prmtl. The introductory paragraph of README.rst could probably benefit from a facelift. This is painfully self-obvious, but...

• This project is pydot-ng rather than merely pydot.
• The project tagline (i.e., slogan) should ideally differentiate this project in some way from the original pydot project: e.g.,

pydot-ng - Next-generation Python interface to Graphviz's Dot language

• Since Ero Carrera (@erocarrera)'s last commit was January 2nd, 2012, the copyright line should be updated to read:

    Ero Carrera (c) 2004-2012
  

• Likewise, since your first commit was February 25th, 2015, a second copyright line assigning current copyrights to you should be added: e.g.,

    Sebastian Kalinowski (c) 2015-2018
  

• Since @erocarrera hasn't been involved in the PyDot world for nearly a decade, it might be more useful to list your contact information rather than ero@dkbza.org.

Altogether, an updated frontispiece might resemble:

pydot-ng - Next-generation Python interface to Graphviz's Dot language

Ero Carrera (c) 2004-2012
Sebastian Kalinowski (c) 2015-2018

sebastian@kalinowski.eu

Thanks for the continued attention! May the last of your Autumn be warm and giddy. 🍂

[leycec]

Also, Poznań looks super-beautiful. I am mildly jealous.