CONTRIBUTING.MD link to section fixed

[gsabatini2016]

Description of the Change

Update the CONTRIBUTING.md file changing the reference "Pulsar and Packages" to the correspondent section.

Release Notes

• In the old version of this file, the "Pulsar and Packages" reference was misconfigured and pointed to nowhere because the person who updated this file has changed the reference name from Atom to Pulsar but the reference still pointing to the section with the old name.

[confused-Techie]

Thanks a ton for contributing! Appreciate you finding something that has seemed to slip through the cracks.

But easy approval as it is in fact correct, so lets get this merged!