Introduced docs changes to indicate Python 3 compatability

docs/tools/offline/cli-setup.md

@@ -7,11 +7,14 @@ You can install Mbed CLI on Windows, Linux and Mac OS X.
 ## Requirements
 
 - **Python:** Mbed CLI is a Python script, so you'll need Python to use it:
-    - We test Mbed CLI with [version 2.7.11 of Python](https://www.python.org/downloads/release/python-2711/). It is not compatible with Python 3.
+    - We test Mbed CLI with [Python versions 2.7.11+ and 3.6.5+](https://www.python.org/downloads/).
     - pip.
+
+    <span class="notes">**Note:** Python 3 usage is **not compatible** with Mbed OS versions older than 5.9 and Mbed CLI toolchain versions older than 1.7.2. </span>
 
     <span class="notes">**Note:** Mbed CLI toolchain versions older than 1.5.1 are **not compatible** with `pip` version 10.0 (or newer). Please use the latest Mbed CLI with newer version of `pip`.</span>
 
+
 - **Git and Mercurial:** Mbed CLI supports both Git and Mercurial repositories, and you may need libraries from both sources as you work, so please to install both:
     - [Git](https://git-scm.com/) - version 1.9.5 or later.
     - [Mercurial](https://www.mercurial-scm.org/) - version 2.2.2 or later.

docs/tools/testing/greentea.md

@@ -10,7 +10,7 @@ This document should help you start using Greentea. Please see the [`htrun` docu
 
 ### Prerequisites
 
-Greentea requires [Python version 2.7](https://www.python.org/downloads/). It supports the following OSes:
+Greentea requires [Python versions 2.7.11+ or 3.6.5+](https://www.python.org/downloads/). It supports the following OSes:
 
 - Windows.
 - Linux (Ubuntu preferred).

docs/tutorials/quickstart/quick-start-cli.md

@@ -8,17 +8,39 @@ The setup process for Arm Mbed CLI depends on your operating system. Please choo
 
 #### Windows
 
-##### 1. Install Mbed CLI
+Two installation methods are available for Windows. The first is a prebuilt installer that you can use quickly. The second installation method is more flexible and allows for greater customization to better fit your system's needs.
+
+##### Prebuilt Mbed CLI installer
 
 Download and run the [Mbed CLI Windows .exe installer](https://mbed-media.mbed.com/filer_public/50/38/5038849b-16a8-42f3-be7a-43d98c7a3af3/mbed_installer_v043.exe).
 
 You can ensure Mbed CLI installed correctly by running `mbed help` from your command-line.
 
 <span class="notes">**Note:** The Windows installer only installs the GNU Arm embedded toolchain. If you want to compile using Arm Compiler 5 or IAR, visit the [supported compilers page](/docs/latest/tools/index.html#compiler-versions).</span>
 
+#### Manual installation
+
+###### 1. Download and install Python and Pip
+
+Download and install [Python versions 2.7.11+ or 3.6.5+](https://www.python.org/downloads/windows/) for Windows. Both Python versions come with their own version of Pip.
+
+<span class="notes">**Note:** When the installer launches, check the checkbox that says **Add Python X.Y to PATH**. Otherwise, Windows does not know where to search for the Python executable.</span>
+
+###### 2. Install a compiler
+
+Download and install a compiler.
+
+<span class="notes">**Note:** To download the latest toolchains, visit the [supported compilers page](/docs/development/tools/index.html#compiler-versions).</span>
+
+###### 3. Install Mbed CLI
+
+To install Mbed CLI, run `pip install mbed-cli` from your command-line.
+
+You can ensure Mbed CLI installed correctly by running `mbed --version`.
+
 ##### 2. Setup environment
 
-For any installed toolchain, be sure to add the Mbed CLI global configuration:
+After installation is complete, be sure to add any available toolchains to Mbed CLI's global configuration. Below is an example using the ARM compiler:
 
 ```
 > mbed config -G ARM_PATH <path to ARM bin\>"
@@ -36,7 +58,7 @@ ARM_PATH=<path to ARM bin\>
 
 ##### 1. Install Python and Pip
 
-Mac OS X 10.8+ comes with Python 2.7 preinstalled by Apple. If you are running an earlier version of Mac OS X, download and install [Python 2.7.12+](https://www.python.org/downloads/mac-osx/).
+Mac OS X 10.8+ comes with Python 2.7 preinstalled by Apple. If you are running an earlier version of Mac OS X, download and install [Python versions 2.7.11+ or 3.6.5+](https://www.python.org/downloads/mac-osx/).
 
 To install Pip, run `sudo easy_install pip` from your command-line.
 
@@ -50,7 +72,7 @@ Download and install a compiler.
 
 To install Mbed CLI, run `pip install mbed-cli` from your command-line.
 
-You can ensure Mbed CLI installed correctly by running `mbed help`.
+You can ensure Mbed CLI installed correctly by running `mbed --version`.
 
 ##### 4. Setup environment
 
@@ -72,12 +94,12 @@ ARM_PATH=<path to ARM bin\>
 
 ##### 1. Install Python and Pip
 
-Download and install [Python 2.7.12+](https://www.python.org/downloads/source/) or run the following from your command-line:
+Download and install [Python versions 2.7.11+ or 3.6.5+](https://www.python.org/downloads/source/), or use your distrubution's package manager to install Python and Pip.
+
+As an example, you can use the following in Ubuntu:
 
 ```console
-$ sudo apt-get install python2.7
-$ sudo apt-get install python-pip
-$ sudo apt-get update
+$ sudo apt-get install python2.7 python-pip
 ```
 
 ##### 2. Install a compiler