Correct PNAS abbrev. (JabRef#4524)

* Correct PNAS abbrev.

* Use long name, PNAS seems non-standard.

src/main/resources/journals/journalList.txt

@@ -12215,7 +12215,7 @@ Proceedings of the Koninklijke Nederlandse Akademie Van Wetenschappen. Series C:
 Proceedings of the Latvian Academy of Sciences, Section B: Natural, Exact and Applied Sciences = Proc. Latv. Acad. Sci. Sect. B
 Proceedings of the Mine Medical Officers Association = Proc. Mine Med. Off. Assoc.
 Proceedings of the Mine Medical Officers Association of SA = Proc. Mine Med. Off. Assoc. SA
-Proceedings of the National academy of Sciences of the United States of America = Proc. Natl. Acad. Sci. U.S.A.
+Proceedings of the National Academy of Sciences of the United States of America = Proc. Natl. Acad. Sci. U.S.A.
 Proceedings of the National Cancer Conference = Proc. Natl. Cancer Conf.
 Proceedings of the National Science Council, Republic of China. Part B, Life Sciences = Proc. Natl. Sci. Counc. Repub. China B
 Proceedings of the Nutrition Society = Proc. Nutr. Soc.