Update README.md

Remove reference to Slate-based tree

Author: jas14

README.md

@@ -6,7 +6,7 @@ This repo powers the official documentation for the Splitwise API. You can view
 
 If something in the API is confusing you, you can open an [issue](https://github.com/splitwise/api-docs/issues) about it on GitHub. We're a small team, so we may not have an instant fix, but we'll get back to you as soon as we're able.
 
-If you spot an issue in our API documentation itself, feel free to open a [pull request](https://github.com/splitwise/api-docs/pulls) to update this repo! Most of the relevant files live in the [/source/includes](https://github.com/splitwise/api-docs/tree/master/source/includes) directory.
+If you spot an issue in our API documentation itself, feel free to open a [pull request](https://github.com/splitwise/api-docs/pulls) to update this repo!
 
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