Fix a-vs-an typos

contrib/seeds/generate-seeds.py

@@ -124,7 +124,7 @@ def main():
     g.write(' * AUTOGENERATED by contrib/seeds/generate-seeds.py\n')
     g.write(' *\n')
     g.write(' * Each line contains a 16-byte IPv6 address and a port.\n')
-    g.write(' * IPv4 as well as onion addresses are wrapped inside a IPv6 address accordingly.\n')
+    g.write(' * IPv4 as well as onion addresses are wrapped inside an IPv6 address accordingly.\n')
     g.write(' */\n')
     with open(os.path.join(indir,'nodes_main.txt'),'r') as f:
         process_nodes(g, f, 'pnSeed6_main', 8333)