Update learning_rate_scheduler_en.rst (#804)

* Update learning_rate_scheduler_en.rst

* Update doc/fluid/api_guides/low_level/layers/learning_rate_scheduler_en.rst
Co-Authored-By: Nacosta123 <42226556+acosta123@users.noreply.github.com>

* Update doc/fluid/api_guides/low_level/layers/learning_rate_scheduler_en.rst
Co-Authored-By: Nacosta123 <42226556+acosta123@users.noreply.github.com>

doc/fluid/api_guides/low_level/layers/learning_rate_scheduler_en.rst

@@ -29,4 +29,8 @@ The following content describes the APIs related to the learning rate scheduler:
 
 * :code:`piecewise_decay`: Piecewise decay. That is, the stair-like decay for a given number of steps, the learning rate stays the same within each step. For related API Reference please refer to :ref:`api_fluid_layers_piecewise_decay`
 
-* :code:`append_LARS`: The learning rate is obtained by the Layer-wise Adaptive Rate Scaling algorithm. For related algorithms, please refer to `Train Feed forward Neural Network with Layerwise Adaptive Rate via Approximating Back-matching Propagation <https://arxiv. Org/abs/1802.09750>`_ . For related API Reference please refer to :ref:`api_fluid_layers_append_LARS`
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+* :code:`append_LARS`: The learning rate is obtained by the Layer-wise Adaptive Rate Scaling algorithm. For related algorithms, please refer to `Train Feed forward Neural Network with Layerwise Adaptive Rate via Approximating Back-matching Propagation <https://arxiv. Org/abs/1802.09750>`_ . For related API Reference please refer to :ref:`api_fluid_layers_append_LARS`
+
+* :code:`cosine_decay`: Cosine attenuation. It means the learning rate changes with the number of steps in the form of a cosine function. For related API Reference please refer to :ref:`api_fluid_layers_cosine_decay`
+
+* :code:`linear_lr_warmup`: The learning rate increases linearly to an appointed rate with the number of steps. For related API Reference please refer to :ref:`api_fluid_layers_linear_lr_warmup`