fixes #286 nng_pair0_open (and all others) need man page

fixes #279 consider restructuring man sections

This represents a rather significant rework, and major editing
effort, for the entire set of manual pages.

All of the pages now have a section number in their filename;
this assists in some other tooling, particularly ebook generation
as every link needs to be programmatically modified when combined
into an ebook.

Section 5 is introduced, and populated with pages for the main
types, and all options are now documented.

Numerous errors have been corrected, including rewriting certain
portions such as the header section of the surveyor protocol.

Much work has been done to facilitate index generation, although
certainly more work remains here.

Every internal link within these pages now resolves; there are no
more dead links.  (This is required to generate Kindle format books.)

1 files changed, 57 insertions, 0 deletions

diff --git a/docs/man/nng_pipe.5.adoc b/docs/man/nng_pipe.5.adoc
new file mode 100644
index 00000000..4befd3e8
--- /dev/null
+++ b/docs/man/nng_pipe.5.adoc
@@ -0,0 +1,57 @@
+= nng_pipe(5)
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This document is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+== NAME
+
+nng_pipe - communications pipe
+
+== SYNOPSIS
+
+[source, c]
+-----------
+#include <nng/nng.h>
+
+typedef uint32_t nng_pipe;
+-----------
+
+== DESCRIPTION
+
+(((pipe)))(((connection)))
+An `nng_pipe` is a handle to a "`pipe`", which can be thought of as a single
+connection.
+(In most cases this is actually the case -- the pipe is an abstraction for a
+single TCP or IPC connection.) 
+Pipes are associated with either the listener or dialer that created them,
+and therefore are also automatically associated with a single socket.
+
+TIP: Most applications should never concern themselves with individual pipes. 
+However it is possible to access a pipe when more information about the
+source of a message is needed, or when more control is required over
+message delivery.
+
+Pipe objects are created by dialers (<<nng_dialer.5#,`nng_dialer`>> objects)
+and listeners (<<nng_listener.5#,`nng_listener`>> objects), which can be
+thought of as "`owning`" the pipe.
+
+Pipe objects may be destroyed by the
+<<nng_pipe_close.3#,`nng_pipe_close()`>> function.
+They are also closed when their "`owning`" dialer or listener is closed,
+or when the remote peer closes the underlying connection.
+
+== SEE ALSO
+
+<<nng_msg_get_pipe.3#,nng_msg_get_pipe(3)>>,
+<<nng_pipe_close.3#,nng_pipe_close(3)>>,
+<<nng_pipe_getopt.3#,nng_pipe_getopt(3)>>,
+<<nng_dialer.5#,nng_dialer(5)>>,
+<<nng_listener.5#,nng_listener(5)>>,
+<<nng_options.5#,nng_options(5)>>,
+<<nng.7#,nng(7)>>