Update app.py

app.py

@@ -112,7 +112,7 @@ arxiv_categories = {
     "hep-th": "high enerty physics - theory",
     "math-ph": "mathematical physics",
     "nlin": "nonlinear sciences",
-    "nlin.AO": "adaptation and Self-organizing systems",
+    "nlin.AO": "adaptation and self-organizing systems",
     "nlin.CD": "chaotic dynamics",
     "nlin.CG": "cellular automata and lattice gases",
     "nlin.PS": "pattern formation and solitons",