Merged PR 1557: Update readme files for dummy data creation

Simple PR to update the readmes used for dummy data creation in the testing folder.

experiments/mlm_bert/README.md

@@ -8,7 +8,7 @@ For this experiment, we can create a dummy dataset by running the
 script located in `testing/create_data.py` as follows:
 
 ```code
-    python create_data.py -e mlm
+    python create_data.py --task mlm_bert
 ```
 
 A couple of scripts are provided in `utils/preprocessing` for preprocessing .tsv files

experiments/nlg_gru/README.md

@@ -8,7 +8,7 @@ For this experiment, we can create a dummy dataset by running the
 script located in `testing/create_data.py` as follows:
 
 ```code
-    python create_data.py -e nlg
+    python create_data.py --task nlg_gru
 ```
 
 A couple of scripts are provided in `utils/preprocessing` for preprocessing .tsv files