Update related-tools.rst

Added to "related tools", seemed the most appropriate place for now.

docs/content/related-tools.rst

@@ -64,4 +64,17 @@ RetroSeq
 is "a tool for discovery and genotyping of transposable element variants (TEVs) 
 (also known as mobile element insertions) from next-gen sequencing reads aligned 
 to a reference genome in BAM format". RetroSeq is developed by Thomas Keane. 
-Source code can be obtained on `GitHub <https://github.com/tk2/RetroSeq>`_.
\ No newline at end of file
+Source code can be obtained on `GitHub <https://github.com/tk2/RetroSeq>`_.
+
+-------------------------
+Intersphinx documentation
+-------------------------
+BEDTools documentation pages are available via Intersphinx (http://sphinx-doc.org/ext/intersphinx.html).
+To enable this, add the following to conf.py in a Sphinx proejct:
+
+    intersphinx_mapping = {'bedtools': ('http://bedtools.readthedocs.org/en/latest/', None)}
+    
+BEDtools documentation links can then be generated with e.g.:
+
+    :ref:`BEDTools:map <bedtools:map>`
+