Add a basic tutorial for the tools in depot_tools.

docs/man1/git-nav-downstream.1

 '\" t
 .\"     Title: git-nav-downstream
 .\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
 .\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
-.\"      Date: 03/25/2014
+.\"      Date: 04/10/2014
 .\"    Manual: Chromium depot_tools Manual
-.\"    Source: depot_tools 207bff1
+.\"    Source: depot_tools 1ce0237
 .\"  Language: English
 .\"
-.TH "GIT\-NAV\-DOWNSTREAM" "1" "03/25/2014" "depot_tools 207bff1" "Chromium depot_tools Manual"
+.TH "GIT\-NAV\-DOWNSTREAM" "1" "04/10/2014" "depot_tools 1ce0237" "Chromium depot_tools Manual"
 .\" -----------------------------------------------------------------
 .\" * Define some portability stuff
 .\" -----------------------------------------------------------------
 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 .\" http://bugs.debian.org/507673
 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 .ie \n(.g .ds Aq \(aq
 .el       .ds Aq '
 .\" -----------------------------------------------------------------
@@ skipping 12 matching lines @@
 .sp
 .nf
 \fIgit nav\-downstream\fR
 .fi
 .sp
 .SH "DESCRIPTION"
 .sp
 \fIgit\-nav\-downstream\fR takes the current branch and discovers all branches downstream of it\&. If there is only one branch downstream of the current branch, the command will check that out\&. If there\*(Aqs more than one downstream branch, the command will prompt you with a selection of the branches\&.
 .SH "EXAMPLE"
 .sp
+
+.sp
 .if n \{\
 .RS 4
 .\}
 .nf
 \fB$ git map\-branches\fR
-\fBorigin/master *\:\fR
-  cool_feature
+\fBorigin/master *
+\fR  cool_feature
     subfeature
-  frozen_changes
-  master
-{NO UPSTREAM}
-  bogus_noparent
+  fixit
+    frozen_branch
 \fB$ git nav\-downstream\fR
-
 Please select a downstream branch
   0\&. cool_feature
-  1\&. frozen_changes
-  2\&. master
-Selection (0\-2)[0]: 0
+  1\&. fixit
+Selection (0\-1)[0]: 0
+Previous HEAD position was 619ccc9\&.\&.\&. Make ReflectorImpl use mailboxes
+Switched to branch \*(Aqcool_feature\*(Aq
+Your branch is ahead of \*(Aqorigin/master\*(Aq by 4 commits\&.
+  (use "git push" to publish your local commits)
 \fB$ git map\-branches\fR
 origin/master
-  \fBcool_feature *\:\fR
-    subfeature
-  frozen_changes
-  master
-{NO UPSTREAM}
-  bogus_noparent
+\fB  cool_feature *
+\fR    subfeature
+  fixit
+    frozen_branch
+\fB$ git nav\-downstream\fR
+Switched to branch \*(Aqsubfeature\*(Aq
+Your branch and \*(Aqcool_feature\*(Aq have diverged,
+and have 2 and 1 different commit each, respectively\&.
+  (use "git pull" to merge the remote branch into yours)
+\fB$ git map\-branches\fR
+origin/master
+  cool_feature
+\fB    subfeature *
+\fR  fixit
+    frozen_branch
 .fi
 .if n \{\
 .RE
 .\}
 .sp
 .SH "SUGGESTED ALIASES"
 .sp
 Some common short\-hand aliases\&. Feel free to add these to your \fI~/\&.gitconfig\fR file\&.
 .sp
 .if n \{\
 .RS 4
 .\}
 .nf
 [alias]
   git down = nav\-downstream
 .fi
 .if n \{\
 .RE
 .\}
 .sp
 .SH "SEE ALSO"
 .sp
 \fBgit-map-branches\fR(1), \fBgit-nav-upstream\fR(1)
 .SH "CHROMIUM DEPOT_TOOLS"
 .sp
-Part of the chromium \fBdepot_tools\fR(1) suite\&. These tools are meant to assist with the development of chromium and related projects\&. Download the tools from \m[blue]\fBhere\fR\m[]\&\s-2\u[1]\d\s+2\&.
+Part of the chromium \fBdepot_tools\fR(7) suite\&. These tools are meant to assist with the development of chromium and related projects\&. Download the tools from \m[blue]\fBhere\fR\m[]\&\s-2\u[1]\d\s+2\&.
 .SH "NOTES"
 .IP " 1." 4
 here
 .RS 4
 \%https://chromium.googlesource.com/chromium/tools/depot_tools.git
 .RE