update nnicli (microsoft#2713)

(cherry picked from commit f82ef62)

docs/en_US/Tutorial/Nnictl.md

@@ -262,7 +262,7 @@ Debug mode will disable version check function in Trialkeeper.
   |Name, shorthand|Required|Default|Description|
   |------|------|------ |------|
   |id|  False| |ID of the experiment you want to set|
-  |--value, -v|  True| |the experiment duration will be NUMBER seconds. SUFFIX may be 's' for seconds (the default), 'm' for minutes, 'h' for hours or 'd' for days.|
+  |--value, -v|  True| | Strings like '1m' for one minute or '2h' for two hours. SUFFIX may be 's' for seconds, 'm' for minutes, 'h' for hours or 'd' for days.|
 
   * Example
 

docs/en_US/conf.py

@@ -17,6 +17,7 @@
 import os
 import sys
 sys.path.insert(0, os.path.abspath('../../src/sdk/pynni'))
+sys.path.insert(1, os.path.abspath('../../src/sdk/pycli'))
 
 
 # -- Project information ---------------------------------------------------

docs/en_US/nnicli_ref.md

@@ -0,0 +1,41 @@
+# NNI Client
+
+NNI client is a python API of `nnictl`, which implements the most commonly used commands. Users can use this API to control their experiments, collect experiment results and conduct advanced analyses based on experiment results in python code directly instead of using command line. Here is an example:
+
+```
+from nnicli import Experiment
+
+# create an experiment instance
+exp = Experiment() 
+
+# start an experiment, then connect the instance to this experiment
+# you can also use `resume_experiment`, `view_experiment` or `connect_experiment`
+# only one of them should be called in one instance
+exp.start_experiment('nni/examples/trials/mnist-pytorch/config.yml', port=9090)
+
+# update the experiment's concurrency
+exp.update_concurrency(3)
+
+# get some information about the experiment
+print(exp.get_experiment_status())
+print(exp.get_job_statistics())
+print(exp.list_trial_jobs())
+
+# stop the experiment, then disconnect the instance from the experiment.
+exp.stop_experiment()
+```
+
+## References
+
+```eval_rst
+..  autoclass:: nnicli.Experiment
+    :members:
+..  autoclass:: nnicli.TrialJob
+    :members:
+..  autoclass:: nnicli.TrialHyperParameters
+    :members:
+..  autoclass:: nnicli.TrialMetricData
+    :members:
+..  autoclass:: nnicli.TrialResult
+    :members:
+```

docs/en_US/sdk_reference.rst

@@ -8,4 +8,5 @@ Python API Reference
 
     Auto Tune <autotune_ref>
     NAS <NAS/NasReference>
-    Compression Utilities <Compressor/CompressionReference>
+    Compression Utilities <Compressor/CompressionReference>
+    NNI Client <nnicli_ref>