doc: changed EFS directory path instructions in documentation and Docstrings (#996)

Author: caxiaohu

doc/overview.rst

@@ -327,7 +327,7 @@ Here are examples of how to use Amazon EFS as input for training:
 
         file_system_input = FileSystemInput(file_system_id='fs-1',
                                             file_system_type='EFS',
-                                            directory_path='tensorflow',
+                                            directory_path='/tensorflow',
                                             file_system_access_mode='ro')
 
         # Start an Amazon SageMaker training job with EFS using the FileSystemInput class
@@ -347,7 +347,7 @@ Here are examples of how to use Amazon EFS as input for training:
 
         records = FileSystemRecordSet(file_system_id='fs-1,
                                       file_system_type='EFS',
-                                      directory_path='kmeans',
+                                      directory_path='/kmeans',
                                       num_records=784,
                                       feature_dim=784)
 
@@ -372,7 +372,7 @@ Here are examples of how to use Amazon FSx for Lustre as input for training:
 
         file_system_input = FileSystemInput(file_system_id='fs-2',
                                             file_system_type='FSxLustre',
-                                            directory_path='tensorflow',
+                                            directory_path='/fsx/tensorflow',
                                             file_system_access_mode='ro')
 
         # Start an Amazon SageMaker training job with FSx using the FileSystemInput class
@@ -392,7 +392,7 @@ Here are examples of how to use Amazon FSx for Lustre as input for training:
 
         records = FileSystemRecordSet(file_system_id='fs-=2,
                                       file_system_type='FSxLustre',
-                                      directory_path='kmeans',
+                                      directory_path='/fsx/kmeans',
                                       num_records=784,
                                       feature_dim=784)
 

src/sagemaker/amazon/amazon_estimator.py

@@ -303,7 +303,7 @@ def __init__(
             file_system_id (str): An Amazon file system ID starting with 'fs-'.
             file_system_type (str): The type of file system used for the input.
                 Valid values: 'EFS', 'FSxLustre'.
-            directory_path (str): Relative path to the root directory (mount point) in
+            directory_path (str): Absolute or normalized path to the root directory (mount point) in
                 the file system. Reference:
                 https://docs.aws.amazon.com/efs/latest/ug/mounting-fs.html and
                 https://docs.aws.amazon.com/efs/latest/ug/wt1-test.html

src/sagemaker/inputs.py

@@ -114,7 +114,7 @@ def __init__(
             file_system_id (str): An Amazon file system ID starting with 'fs-'.
             file_system_type (str): The type of file system used for the input.
                 Valid values: 'EFS', 'FSxLustre'.
-            directory_path (str): Relative path to the root directory (mount point) in
+            directory_path (str): Absolute or normalized path to the root directory (mount point) in
                 the file system.
                 Reference: https://docs.aws.amazon.com/efs/latest/ug/mounting-fs.html and
                 https://docs.aws.amazon.com/fsx/latest/LustreGuide/mount-fs-auto-mount-onreboot.html