replace 'mkdir' with 'mkdir -p' (#997)

Summary:
Allow shell script to create sub directories with -p flag. Amends readme file too.
Pull Request resolved: https://github.com/pytorch/fairseq/pull/997

Differential Revision: D16710813

Pulled By: myleott

fbshipit-source-id: 89abefa27e8fac99d212fc9b7b0dbc3690043ba0

examples/roberta/preprocess_GLUE_tasks.sh

@@ -84,7 +84,7 @@ do
 
   # Strip out header and filter lines that don't have expected number of fields.
   rm -rf "$TASK_DATA_FOLDER/processed"
-  mkdir "$TASK_DATA_FOLDER/processed"
+  mkdir -p "$TASK_DATA_FOLDER/processed"
   for SPLIT in $SPLITS
   do
     # CoLA train and dev doesn't have header.
@@ -178,7 +178,7 @@ do
       --workers 60;
   else
     # For STS-B output range is converted to be between: [0.0, 1.0]
-    mkdir "$TASK-bin/label"
+    mkdir -p "$TASK-bin/label"
     awk '{print $1 / 5.0 }' "$TASK_DATA_FOLDER/processed/train.label" > "$TASK-bin/label/train.label"
     awk '{print $1 / 5.0 }' "$TASK_DATA_FOLDER/processed/dev.label" > "$TASK-bin/label/valid.label"
   fi

examples/scaling_nmt/README.md

@@ -17,7 +17,7 @@ Then:
 1. Extract the WMT'16 En-De data:
 ```bash
 TEXT=wmt16_en_de_bpe32k
-mkdir $TEXT
+mkdir -p $TEXT
 tar -xzvf wmt16_en_de.tar.gz -C $TEXT
 ```