build+docs: align minimum requirements with ndn-cxx/NFD

 * Recommend boost >= 1.65.1 and gcc >= 7.4.0
 * Require clang >= 4.0, or Xcode >= 9.0 on macOS
 * Silence an ABI-related diagnostic message from gcc on armv7
 * Update waf to version 2.0.21
 * Make graphviz optional for building documentation
 * Sync sphinx configuration

Change-Id: Ib271da841cd12e7595ae83d75bd0fc681f8c231f
diff --git a/docs/manpages.rst b/docs/manpages.rst
index e2e1582..ac08dce 100644
--- a/docs/manpages.rst
+++ b/docs/manpages.rst
@@ -1,10 +1,8 @@
-.. _Manpages:
-
-Manpages
-========
+Man pages
+=========
 
 .. toctree::
-   manpages/nlsr
-   manpages/nlsr.conf
-   manpages/nlsrc
+   :glob:
    :maxdepth: 1
+
+   manpages/*