unify installation instructions (Project-MONAI#1524)

Signed-off-by: Richard Brown <33289025+rijobro@users.noreply.github.com>

README.md

@@ -30,23 +30,13 @@ Its ambitions are:
 
 ## Installation
 
-### Installing [the current release](https://pypi.org/project/monai/):
-```bash
-pip install monai
-```
+To install [the current release](https://pypi.org/project/monai/), you can simply run:
 
-### Installing the master branch from the source code repository:
 ```bash
-pip install git+https://github.com/Project-MONAI/MONAI#egg=MONAI
+pip install monai
 ```
 
-### Using the pre-built Docker image [DockerHub](https://hub.docker.com/r/projectmonai/monai):
-  ```bash
-  # with docker v19.03+
-  docker run --gpus all --rm -ti --ipc=host projectmonai/monai:latest
-  ```
-
-For more details, please refer to [the installation guide](https://docs.monai.io/en/latest/installation.html).
+For other installation methods (using the master branch, using Docker, etc.), please refer to [the installation guide](https://docs.monai.io/en/latest/installation.html).
 
 ## Getting Started
 

docs/source/installation.md

@@ -1,17 +1,24 @@
 # Installation guide
 
+## Table of Contents
+1. [From PyPI](#from-pypi)
+	1. [Milestone release](#milestone-release)
+	2. [Weekly preview release](#weekly-preview-release)
+2. [From GitHub](#from-github)
+	1. [System-wide](#milestone-release)
+	2. [Editable](#weekly-preview-release)
+3. [Validating the install](#validating-the-install)
+4. [MONAI version string](#monai-version-string)
+5. [From DockerHub](#from-dockerhub)
+6. [Installing the recommended dependencies](#Installing-the-recommended-dependencies)
+
+---
+
 MONAI's core functionality is written in Python 3 (>= 3.6) and only requires [Numpy](https://numpy.org/) and [Pytorch](https://pytorch.org/).
 
 The package is currently distributed via Github as the primary source code repository,
 and the Python package index (PyPI). The pre-built Docker images are made available on DockerHub.
 
-This page provides steps to:
-- [Install MONAI from PyPI](#from-pypi)
-- [Install MONAI from GitHub](#from-github)
-- [Validate the install](#validating-the-install)
-- [Understand MONAI version string](#monai-version-string)
-- [Run MONAI From DockerHub](#from-dockerhub)
-
 To install optional features such as handling the NIfTI files using
 [Nibabel](https://nipy.org/nibabel/), or building workflows using [Pytorch
 Ignite](https://pytorch.org/ignite/), please follow the instructions: