Update contributing docs with how to run a specific test and debug in…

… VSCode (palantir#2025)

docs/develop/contributing/index.md

@@ -19,3 +19,26 @@ The [`next` branch of the TSLint repo](https://github.com/palantir/tslint/tree/n
 compiler as a `devDependency`. This allows you to develop the linter and its rules against the latest features of the
 language. Releases from this branch are published to NPM with the `next` dist-tag, so you can get the latest dev
 version of TSLint via `npm install tslint@next`.
+
+#### Running a specific test
+
+You can test a specific test by using the `--test` command line parameter followed by your test directory. For example:
+```
+// global tslint
+// point to a dir that has tslint.json and .lint files
+tslint --test test/rules/semicolon/always
+
+// locally built tslint
+./bin/tslint --test test/rules/semicolon/always
+```
+
+#### Debugging in Visual Studio Code
+
+Configuration files to work with Visual Studio Code are included when you check out the source code. These files live in the `.vscode` directory. To run TSLint in the debugger, switch to Debug view and use the dropdown at the top of the Debug pane to select the launch configuration (specified in `.vscode/launch.json`). Press `F5` to debug. You should be able to set breakpoints and debug as usual.
+
+The current debug configurations are:
+
+- Debug CLI: Used to debug TSLint using command line arguments. Modify the `args` array in `.vscode/launch.json` to add arguments.
+- Debug Mocha Tests: Runs non-rule tests
+- Debug Rule Tests: Runs rule tests (under `test/rules`)
+- Deubg Document Generation: Debug the `scripts/buildDocs.ts` script.