Help: Add guides for user interaction

Add some prose to the documentation index page to guide readers to the
major manuals and guides.

Add a new "User Interaction Guide" to help the class of new user
who wishes to build a project with CMake for the first time, such as
after cloning a repo from a git repository.

Add a new "Using Dependencies Guide" to help the class of new
user who wishes to consume a SDK provided by a third party and needs a
starting point.  This is a different type of user to the user who wishes
to create their own project from scratch (addressed by the
`cmake-buildsystem(7)` manual) as each will encounter needs for
information discovery in a different order.

1 files changed, 31 insertions, 0 deletions

diff --git a/Help/index.rst b/Help/index.rst
index cc6cee6..4d9a9c8 100644
--- a/Help/index.rst
+++ b/Help/index.rst
@@ -1,5 +1,34 @@
 .. title:: CMake Reference Documentation
 
+Introduction
+############
+
+CMake is a tool to manage building of source code.  Originally, CMake was
+designed as a generator for various dialects of ``Makefile``, today
+CMake generates modern buildsystems such as ``Ninja`` as well as project
+files for IDEs such as Visual Studio and Xcode.
+
+CMake is widely used for the C and C++ languages, but it may be used to
+build source code of other languages too.
+
+People encountering CMake for the first time may have different initial
+goals.  To learn how to build a source code package downloaded from the
+internet, start with the :guide:`User Interaction Guide`.
+This will detail the steps needed to run the :manual:`cmake(1)` or
+:manual:`cmake-gui(1)` executable and how to choose a generator, and
+how to complete the build.
+
+The :guide:`Using Dependencies Guide` is aimed at developers
+wishing to get started using a third-party library.
+
+For developers starting a project using CMake, the :guide:`CMake Tutorial`
+is a suitable starting point.  The :manual:`cmake-buildsystem(7)`
+manual is aimed at developers expanding their knowledge of maintaining
+a buildsystem and becoming familiar with the build targets that
+can be represented in CMake.  The :manual:`cmake-packages(7)` manual
+explains how to create packages which can easily be consumed by
+third-party CMake-based buildsystems.
+
 Command-Line Tools
 ##################
 
@@ -53,6 +82,8 @@ Reference Manuals
     :maxdepth: 1
 
     /guide/tutorial/index
+    /guide/user-interaction/index
+    /guide/using-dependencies/index
 
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