Add ToC to contributing.md

Author: zbeekman

CONTRIBUTING.md

@@ -2,10 +2,22 @@
 
 Looking to contribute something to [json-fortran](README.md)? **Here's how you can help.**
 
+<!-- markdown-toc start - Don't edit this section. Run M-x markdown-toc/generate-toc again -->
+**Table of Contents**
+
+  - [Key Branches](#key-branches)
+  - [Filing issues](#filing-issues)
+  - [Outstanding Work](#outstanding-work)
+  - [Pull Requests](#pull-requests)
+  - [Coding Standards](#coding-standards)
+
+<!-- markdown-toc end -->
+
 ## Key Branches
 
 - `master` is the latest, development version and all efforts should be made to keep it stable.
 
+[top](#contributing-to-json-fortran)
 ## Filing issues
 
 - Before filing a new [issue](https://github.com/jacobwilliams/json-fortran/issues), please perform a search to see if that issue has already been filed by someone else, and whether or not a solution exists. If you are experiencing the same issue as one that's already posted, please leave any additional comments and information under the existing issue. If your issue is related to a previous issue, but substantively different, file a new issue and include a mention of the related issue in text, using GitHub's `#<issue-number>` syntax.
@@ -16,10 +28,12 @@ Looking to contribute something to [json-fortran](README.md)? **Here's how you c
   1. If applicable, what compiler you used, and any non-standard options or configurations that were used.
   1. All steps required to reproduce the problem
 
+[top](#contributing-to-json-fortran)
 ## Outstanding Work
 
 - Take a look at the [issues](https://github.com/jacobwilliams/json-fortran/issues) to see if there is an issue you'd like to help address. [Issues](https://github.com/jacobwilliams/json-fortran/issues) with the [ready label](https://github.com/jacobwilliams/json-fortran/issues?q=is%3Aopen+is%3Aissue+label%3A%22ready%22) or in the [ready column on waffle.io](https://waffle.io/jacobwilliams/json-fortran) are issues that are ready to be dealt with. (i.e., They are not blocked by other dependencies and are higher priority.)
 
+[top](#contributing-to-json-fortran)
 ## Pull Requests
 
 - Try not to pollute your pull request with unintended changes--keep them simple and small
@@ -38,6 +52,7 @@ git rebase upstream
 - Pull requests are tested by our [travis-ci](https://travis-ci.org/jacobwilliams/json-fortran) continuous integration system, and any errors uncovered will need to be fixed before the pull request can be merged into master.
 - The json-fortran library and associated documentation is released under a BSD style [license](https://github.com/jacobwilliams/json-fortran/blob/master/LICENSE).  By submitting a pull request, you are agreeing to release your code under the same license.  Note that code with GPL or other "copyleft" style licenses will not be accepted.
 
+[top](#contributing-to-json-fortran)
 ## Coding Standards
 
 - Each commit should address a single logical change and code base transformation.
@@ -48,4 +63,6 @@ git rebase upstream
 - *Do NOT* allow your editor to make a bunch of indentation or white space changes, that will introduce non-substantive changes on lines that you have not actually edited.
 - The coding style is modern free-form Fortran, consistent with the Fortran 2008 standard.  Note that the two supported compilers (ifort and gfortran) do not currently include the entire Fortran 2008 standard. Therefore, only those language features supported by Gfortran 4.9 and Intel 13.1.0 are currently allowed.  This also means that previous versions of these compilers are not supported, and major changes to the code to support earlier compilers (or Fortran 95) will not be accepted.  At some point in the future (when compiler support has improved), all Fortran 2008 features will be allowed.
 - All subroutines and functions *must* be properly documented.  This includes useful inline comments as well as comment blocks using the [ROBODoc](http://rfsber.home.xs4all.nl/Robo/manual.html) syntax.
-- For simplicity, json-fortran currently consists of one module file. It is not envisioned that it will ever need to expand to include multiple files (if it does, there would need to be a very good reason).
+- For simplicity, json-fortran currently consists of one module file. It is not envisioned that it will ever need to expand to include multiple files (if it does, there would need to be a very good reason).
+
+[top](#contributing-to-json-fortran)