Remove nonexistent link from contributing guide

[ches]

development/README.md does not exist in the repository, and it doesn't appear that it ever has, so I assume this was copypasta from another project. If there's a document that this is supposed to refer to I'll update the link instead if someone points out to me what it is.

I'm not sure if there's a [ci skip] type of commit message annotation for Concourse, if there is and it should be used I can update this commit.

Also, while I'm here, is there a public repo for the http://lattice.cf/ site? I saw a few small typos/grammar fixes I was planning to submit when I actually looked at the contributing guide in the first place 😄 If there's a repo or a gh-pages branch or the like somewhere, it wasn't obvious to me.

[cfdreddbot]

Hey ches!

Thanks for submitting this pull request!

All pull request authors must have a Contributor License Agreement (CLA) on-file with us. Please sign the appropriate CLA (individual or corporate).

When sending signed CLA please provide your github username in case of individual CLA or the list of github usernames that can make pull requests on behalf of your organization.

If you are confident that you're covered under a Corporate CLA, please make sure you've publicized your membership in the appropriate Github Org, per these instructions.

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this. You can view the current status of your issue at: https://www.pivotaltracker.com/story/show/108756428.

[ches]

FYI I have submitted my individual CLA by email already, just a few minutes ago so surely awaiting processing.

[keaty]

Hi ches, thanks for your interest in fixing up our documentation. lattice.cf isn't an open source repo yet, so you're not missing anything there, but I've merged your pull request for contributing.md (you're probably right about the copypasta).

[ches]

Thanks @keaty, I'll keep an eye open for a lattice.cf repo in the future.