Rearrange README.md a bit and make it work better in the doxygen generated docs.

Also, add a table of contents, and a brief section on using json-c with links to
the header files most likely to be useful.

README.md

@@ -1,19 +1,27 @@
 `json-c`                       {#mainpage}
 ========
 
-JSON-C - A JSON implementation in C
+1. [Overview and Build Status](#overview)
+2. [Building on Unix](#buildunix)
+3. [Install Prerequisites](#installprereq)
+4. [Building with partial threading support](#buildthreaded)
+5. [Linking to libjson-c](#linking)
+6. [Using json-c](#using)
+
+JSON-C - A JSON implementation in C <a name="overview"></a>
 -----------------------------------
 
 Build Status
-* [![AppVeyor Build Status](https://ci.appveyor.com/api/projects/status/github/json-c/json-c?branch=master&svg=true)](https://ci.appveyor.com/project/hawicz/json-c)
+* [AppVeyor Build](https://ci.appveyor.com/project/hawicz/json-c) ![AppVeyor Build Status](https://ci.appveyor.com/api/projects/status/github/json-c/json-c?branch=master&svg=true)
-* [![Travis Build Status](https://travis-ci.org/json-c/json-c.svg?branch=master)](https://travis-ci.org/json-c/json-c)
+* [Travis Build](https://travis-ci.org/json-c/json-c) ![Travis Build Status](https://travis-ci.org/json-c/json-c.svg?branch=master)
 
 JSON-C implements a reference counting object model that allows you to easily 
 construct JSON objects in C, output them as JSON formatted strings and parse 
 JSON formatted strings back into the C representation of JSON objects.
 It aims to conform to [RFC 7159](https://tools.ietf.org/html/rfc7159).
 
-Building on Unix with `git`, `gcc` and `autotools`
+
+Building on Unix with `git`, `gcc` and `autotools` <a name="buildunix"></a>
 --------------------------------------------------
 
 Home page for json-c: https://github.com/json-c/json-c/wiki
@@ -28,10 +36,13 @@ See also the "Installing prerequisites" section below.
 If you're not using a release tarball, you'll also need:
 
  - `autoconf>=2.64` (`autoreconf`)
- - `automake>=1.10.3`
+ - `automake>=1.13`
 
 Make sure you have a complete `libtool` install, including `libtoolize`.
 
+To generate docs (e.g. as part of make distcheck) you'll also need:
+ - `doxygen>=1.8.13`
+
 ### Build instructions:
 
 `json-c` GitHub repo: https://github.com/json-c/json-c
@@ -54,48 +65,10 @@ To build and run the test programs:
 
 ```sh
 $ make check
+$ make USE_VALGRIND=0 check   # optionally skip using valgrind
 ```
 
-Building with partial threading support
+Install prerequisites <a name="installprereq"></a>
-----------------------------------------
-
-Although json-c does not support fully multi-threaded access to
-object trees, it has some code to help make use in threaded programs
-a bit safer.  Currently, this is limited to using atomic operations for
-json_object_get() and json_object_put().
-
-Since this may have a performance impact, of at least 3x slower
-according to https://stackoverflow.com/a/11609063, it is disabled by
-default.  You may turn it on by adjusting your configure command with:
-   --enable-threading
-
-Separately, the default hash function used for object field keys,
-lh_char_hash, uses a compare-and-swap operation to ensure the randomly
-seed is only generated once.  Because this is a one-time operation, it
-is always compiled in when the compare-and-swap operation is available.
-
-
-Linking to `libjson-c`
-----------------------
-
-If your system has `pkgconfig`,
-then you can just add this to your `makefile`:
-
-```make
-CFLAGS += $(shell pkg-config --cflags json-c)
-LDFLAGS += $(shell pkg-config --libs json-c)
-```
-
-Without `pkgconfig`, you would do something like this:
-
-```make
-JSON_C_DIR=/path/to/json_c/install
-CFLAGS += -I$(JSON_C_DIR)/include/json-c
-LDFLAGS+= -L$(JSON_C_DIR)/lib -ljson-c
-```
-
-
-Install prerequisites
 -----------------------
 
 If you are on a relatively modern system, you'll likely be able to install
@@ -142,3 +115,59 @@ export PATH=${HOME}/ac_install/bin:$PATH
   make install)
 ```
 
+
+Building with partial threading support <a name="buildthreaded"></a>
+----------------------------------------
+
+Although json-c does not support fully multi-threaded access to
+object trees, it has some code to help make use in threaded programs
+a bit safer.  Currently, this is limited to using atomic operations for
+json_object_get() and json_object_put().
+
+Since this may have a performance impact, of at least 3x slower
+according to https://stackoverflow.com/a/11609063, it is disabled by
+default.  You may turn it on by adjusting your configure command with:
+   --enable-threading
+
+Separately, the default hash function used for object field keys,
+lh_char_hash, uses a compare-and-swap operation to ensure the randomly
+seed is only generated once.  Because this is a one-time operation, it
+is always compiled in when the compare-and-swap operation is available.
+
+
+Linking to `libjson-c` <a name="linking">
+----------------------
+
+If your system has `pkgconfig`,
+then you can just add this to your `makefile`:
+
+```make
+CFLAGS += $(shell pkg-config --cflags json-c)
+LDFLAGS += $(shell pkg-config --libs json-c)
+```
+
+Without `pkgconfig`, you would do something like this:
+
+```make
+JSON_C_DIR=/path/to/json_c/install
+CFLAGS += -I$(JSON_C_DIR)/include/json-c
+LDFLAGS+= -L$(JSON_C_DIR)/lib -ljson-c
+```
+
+
+Using json-c <a name="using">
+------------
+
+To use json-c you can either include json.h, or preferrably, one of the
+following more specific header files:
+
+* json_object.h  - Core types and methods.
+* json_tokener.h - Methods for parsing and serializing json-c object trees.
+* json_pointer.h - JSON Pointer (RFC 6901) implementation for retrieving
+                   objects from a json-c object tree.
+* json_object_iterator.h - Methods for iterating over single json_object instances.
+* json_visit.h   - Methods for walking a tree of json-c objects.
+* json_util.h    - Miscelleanous utility functions.
+
+For a full list of headers see [files.html](files.html)
+