Fix typos in external-libraries.txt file

[parammittal16]

JabRef version on

• I have tested the latest development version from http://builds.jabref.org/master/ and the problem persists

Grammatical typos in the external-libraries.txt file

Steps to reproduce the behavior:

1. Fix typos

Log File

Paste an excerpt of your log file here

[koppor]

Thank you for reporting. In this project, it is not mandatory to open an issue of a problem one fixes directly afterwards.

Did you check our https://github.com/JabRef/jabref/blob/master/CONTRIBUTING.md - we do not require to open an issue.

Another #hacktoberfest learning: Read CONTRIBUTING.md of a repository. 🎉