doc: import chapters from aptly.info

docs/Graph.md

@@ -1,4 +1,30 @@
 # Dependency Graph
 <div>
+aptly generates graph showing dependencies between mirrors, local repositories,
+snapshots and published repositories.
+ 
+
+Command graph generates graph of dependencies:
+
+* between snapshots and mirrors (what mirror was used to create each snapshot)
+* between snapshots and local repos (what local repo was used to create snapshot)
+* between snapshots (pulling, merging, etc.)
+* between snapshots, local repos and published repositories (how snapshots were published).
+
+Graph is rendered to PNG file using graphviz package.
+
+Usage:
+
+    $ aptly graph
+
+Flags:
+
+-   `-format="png"`: graph output format, could be anything graphviz supports, e.g. `png`, `pdf`, `svg`, ...
+-   `-output=""`: specify output filename, default is to open result in viewer
+-   `-layout="horizontal"`: change between a `horizontal` and a `vertical` graph layout.
+
+Example:
+
+<a href="../../../img/graphfull.png"><img src="../../../img/graph.png" alt="Example graph from aptly graph (horizontal)" class="img-responsive"></a>
 
 </div>