fix doc mistakes and broken links.

docs/GetStarted.md

@@ -38,7 +38,7 @@ An experiment is to run multiple trial jobs, each trial job tries a configuratio
 
 This command will be filled in the yaml configure file below. Please refer to [here]() for how to write your own trial.
 
-**Prepare tuner**: NNI supports several popular automl algorithms, including Random Search, Tree of Parzen Estimators (TPE), Evolution algorithm etc. Users can write their own tuner (refer to [here](CustomizedTuner.md)), but for simplicity, here we choose a tuner provided by NNI as below:
+**Prepare tuner**: NNI supports several popular automl algorithms, including Random Search, Tree of Parzen Estimators (TPE), Evolution algorithm etc. Users can write their own tuner (refer to [here](howto_2_CustomizedTuner.md), but for simplicity, here we choose a tuner provided by NNI as below:
 
       tuner:
         builtinTunerName: TPE

docs/InstallNNI_Ubuntu.md

@@ -9,12 +9,10 @@
       wget
 
     python pip should also be correctly installed. You could use "which pip" or "pip -V" to check in Linux.
-
-    * Note: we don't support virtual environment in current releases.
 
 * __Install NNI through pip__
 
-      pip3 install -v --user git+https://github.com/Microsoft/nni.git@v0.1
+      pip3 install -v --user git+https://github.com/Microsoft/nni.git@v0.2
       source ~/.bashrc
 
 * __Install NNI through source code__

docs/howto_2_CustomizedTuner.md

@@ -1,4 +1,4 @@
-# Customized Tuner for Experts
+# **How To** - Customize Your Own Tuner
 
 *Tuner receive result from Trial as a matric to evaluate the performance of a specific parameters/architecture configure. And tuner send next hyper-parameter or architecture configure to Trial.*