Update docs of building from source (#4004)

Author: liuzhe-lz

docs/en_US/Tutorial/InstallationLinux.rst

@@ -26,7 +26,8 @@ Install NNI through source code
 
      git clone -b v2.3 https://github.com/Microsoft/nni.git
      cd nni
-     python3 -m pip install --upgrade pip setuptools
+     python3 -m pip install -U -r dependencies/setup.txt
+     python3 -m pip install -r dependencies/develop.txt
      python3 setup.py develop
 
 Build wheel package from NNI source code
@@ -40,7 +41,8 @@ If you want to perform a persist install instead, we recommend to build your own
     git clone -b v2.3 https://github.com/Microsoft/nni.git
     cd nni
     export NNI_RELEASE=2.0
-    python3 -m pip install --upgrade pip setuptools wheel
+    python3 -m pip install -U -r dependencies/setup.txt
+    python3 -m pip install -r dependencies/develop.txt
     python3 setup.py clean --all
     python3 setup.py build_ts
     python3 setup.py bdist_wheel -p manylinux1_x86_64

docs/en_US/Tutorial/InstallationWin.rst

@@ -42,6 +42,8 @@ If you want to contribute to NNI, refer to `setup development environment <Setup
 
        git clone -b v2.3 https://github.com/Microsoft/nni.git
        cd nni
+       python -m pip install -U -r dependencies/setup.txt
+       python -m pip install -r dependencies/develop.txt
        python setup.py develop
 
 Verify installation

docs/en_US/Tutorial/SetupNniDeveloperEnvironment.rst

@@ -20,7 +20,8 @@ Note, if you want to contribute code back, it needs to fork your own NNI repo, a
 
 .. code-block:: bash
 
-   python3 -m pip install --upgrade pip setuptools
+   python3 -m pip install -U -r dependencies/setup.txt
+   python3 -m pip install -r dependencies/develop.txt
    python3 setup.py develop
 
 This installs NNI in `development mode <https://setuptools.readthedocs.io/en/latest/userguide/development_mode.html>`__,

setup.py

@@ -9,6 +9,14 @@
 If release version is not set, default to a development build whose version string will be `999.dev0`.
 
 
+## Prepare Environment ##
+
+Install development dependencies:
+
+  $ pip install -U -r dependencies/setup.txt
+  $ pip install -r dependencies/develop.txt
+
+
 ## Development ##
 
 Build and install for development:
@@ -23,7 +31,7 @@
 
   $ python setup.py clean [--all]
 
-Build TypeScript modules without install:
+Compile TypeScript modules without re-install:
 
   $ python setup.py build_ts