Update config.json

Changed "task_specific_params : summarization : max_length" to 300 to help finish summaries that were otherwise being cut off.

config.json

@@ -29,7 +29,7 @@
     "summarization": {
       "early_stopping": true,
       "length_penalty": 2.0,
-      "max_length": 200,
+      "max_length": 300,
       "min_length": 30,
       "no_repeat_ngram_size": 3,
       "num_beams": 4,