doc: Mention the pronunciation of "Guix".

* README: Mention pronunciation of "Guix".
* doc/guix.texi (Introduction): Likewise.

README

 -*- mode: org -*-
 
-[[http://www.gnu.org/software/guix/][GNU Guix]] is a purely functional package manager, and associated free
-software distribution, for the [[http://www.gnu.org/gnu/gnu.html][GNU system]].  In addition to standard
-package management features, Guix supports transactional upgrades and
-roll-backs, unprivileged package management, per-user profiles, and
-garbage collection.
+[[http://www.gnu.org/software/guix/][GNU Guix]] (IPA: /ɡiːks/) is a purely functional package manager, and
+associated free software distribution, for the [[http://www.gnu.org/gnu/gnu.html][GNU system]].  In addition
+to standard package management features, Guix supports transactional
+upgrades and roll-backs, unprivileged package management, per-user
+profiles, and garbage collection.
 
 It provides [[http://www.gnu.org/software/guile/][Guile]] Scheme APIs, including a high-level embedded
 domain-specific languages (EDSLs) to describe how packages are to be

doc/guix.texi

@@ -78,12 +78,14 @@ package management tool written for the GNU system.
 @node Introduction
 @chapter Introduction
 
-GNU Guix is a functional package management tool for the GNU system.
-Package management consists in all the activities that relate to
-building packages from source, honoring the build-time and run-time
-dependencies on packages, installing packages in user environments,
-upgrading installed packages to new versions or rolling back to a
-previous set, removing unused software packages, etc.
+GNU Guix@footnote{``Guix'' is pronounced like ``geeks'', or ``ɡiːks''
+using the international phonetic alphabet (IPA).} is a functional
+package management tool for the GNU system.  Package management consists
+in all the activities that relate to building packages from source,
+honoring the build-time and run-time dependencies on packages,
+installing packages in user environments, upgrading installed packages
+to new versions or rolling back to a previous set, removing unused
+software packages, etc.
 
 @cindex functional package management
 The term @dfn{functional} refers to a specific package management