Fix small doc typos. (#145)

Author: lizroth

src/aws_encryption_sdk/materials_managers/base.py

@@ -33,7 +33,7 @@ def get_encryption_materials(self, request):
         :param request: encryption materials request
         :type request: aws_encryption_sdk.materials_managers.EncryptionMaterialsRequest
         :returns: encryption materials
-        :rtype: aws_ecryption_sdk.materials_managers.EncryptionMaterials
+        :rtype: aws_encryption_sdk.materials_managers.EncryptionMaterials
         """
 
     @abc.abstractmethod

src/aws_encryption_sdk/materials_managers/caching.py

@@ -179,7 +179,7 @@ def get_encryption_materials(self, request):
         :param request: Encryption materials request
         :type request: aws_encryption_sdk.materials_managers.EncryptionMaterialsRequest
         :returns: encryption materials
-        :rtype: aws_ecryption_sdk.materials_managers.EncryptionMaterials
+        :rtype: aws_encryption_sdk.materials_managers.EncryptionMaterials
         """
         if not self._should_cache_encryption_request(request):
             return self.backing_materials_manager.get_encryption_materials(request)

src/aws_encryption_sdk/materials_managers/default.py

@@ -64,7 +64,7 @@ def get_encryption_materials(self, request):
         :param request: encryption materials request
         :type request: aws_encryption_sdk.materials_managers.EncryptionMaterialsRequest
         :returns: encryption materials
-        :rtype: aws_ecryption_sdk.materials_managers.EncryptionMaterials
+        :rtype: aws_encryption_sdk.materials_managers.EncryptionMaterials
         :raises MasterKeyProviderError: if no master keys are available from the underlying master key provider
         :raises MasterKeyProviderError: if the primary master key provided by the underlying master key provider
             is not included in the full set of master keys provided by that provider