Copy edit GattAttribute.h

Make minor copy edits for active voice and phrasing.

Author: Amanda Butler

features/FEATURE_BLE/ble/GattAttribute.h

@@ -37,7 +37,7 @@ class GattAttribute {
 public:
     /**
      * Type for the handle or ID of the attribute in the ATT table. These are
-     * unique and are usually generated by the underlying BLE stack.
+     * unique, and the underlying BLE stack usually generates them.
      */
     typedef ble::attribute_handle_t Handle_t;
     /**
@@ -59,7 +59,7 @@ class GattAttribute {
      *  @param[in]  maxLen
      *              The max length in bytes of this attribute's value.
      *  @param[in]  hasVariableLen
-     *              Whether the attribute's value length changes overtime.
+     *              Whether the attribute's value length changes over time.
      *
      *  @section EXAMPLE
      *