Document the extra NL that sometimes comes with a descriptor

This NL isn't so easy to remove in Tor, since some older
control-port code depends on it IIRC.  But not having documented it
caused arti#637: let's explain that, so that the next unfortunate
implementor doesn't hit it.

1 files changed, 6 insertions, 0 deletions

diff --git a/dir-spec.txt b/dir-spec.txt
index d2f6c4e..d574e3f 100644
--- a/dir-spec.txt
+++ b/dir-spec.txt
@@ -487,6 +487,12 @@ Table of Contents
    accepted and ignored.  Many of the nonterminals below are defined in
    section 2.1.3.
 
+   Note that many versions of Tor will generate an extra newline at the
+   end of their descriptors.  Implementations MUST tolerate one or
+   more blank lines at the end of a single descriptor or a list of
+   concatenated descriptors.  New implementations SHOULD NOT generate
+   such blank lines.
+
      "router" nickname address ORPort SOCKSPort DirPort NL
 
        [At start, exactly once.]