doc: Fix overfull hboxes errors that cause PDF build to return fail

* overfull hboxes cause texi2dvi to return fail, even if the PDf is written.
  We hacked around this by running it with '...  || true', but that
  sucks for buildboting the docs.

  Fix all the overfull hboxes.

* ospfd.texi: Long command definitions can cause hbox overruns in the
  columnar command definitions index.  This leads to strange errors
  about "Missing number, treated as zero." when building the index -
  very hard to figure out.

  'show ip ospf database ...' was the culprit.  Use a distinct deffnx
  alias for each option instead of trying to stuff them into 1 line.
diff --git a/doc/main.texi b/doc/main.texi
index 849773b..6d42c04 100644
--- a/doc/main.texi
+++ b/doc/main.texi
@@ -355,11 +355,11 @@
 when installing in the kernel.
 @end deffn
 
-@example
 The following creates a prefix-list that matches all addresses, a route-map
 that sets the preferred source address, and applies the route-map to all
 @command{rip} routes.
 
+@example
 @group
 ip prefix-list ANY permit 0.0.0.0/0 le 32
 route-map RM1 permit 10