Adding GuardRails docs (#44)

docs/source/main/mythx-for-smart-contract-developers.rst

@@ -13,6 +13,7 @@ Current tools
 
    ../tooling/truffle
    ../tooling/remix
+   ../tooling/guardrails
    ../tooling/mythos
    ../tooling/pythx-cli
 

docs/source/tooling/guardrails.rst

@@ -0,0 +1,54 @@
+.. _tools.guardrails:
+
+Guardrails
+==========
+
+GuardRails is a service that provides continuous security feedback for your GitHub repositories.
+
+.. image:: img/guardrails.png
+
+What is GuardRails?
+-------------------
+
+`Guardrails <https://guardrails.io>`_ makes open-source security tools easily available in your GitHub pull requests. It has been tuned to keep the noise low and only report high-impact and relevant security issues.
+
+Installing and configuring security tools, even for one repository, typically takes a lot of time and effort. GuardRails makes that process painless and rewarding for developers.
+
+GuardRails can be installed across all your repositories in minutes. Once installed, GuardRails identifies security problems in your codebase and helps you fix them.
+
+In addition, GuardRails leverages the power of MythX in order to scan for security vulnerabilities in your smart contracts.
+
+Setup
+-----
+
+To view to latest setup instructions for GuardRails, please see their `Getting Started <https://www.guardrails.io/docs/en/getting-started>`_ page.
+
+.. note:: The free version of GuardRails only works with public repositories.
+
+MythX comes built-in to GuardRails integration; **no special installation is required.**
+
+Configuration
+-------------
+
+By default GuardRails will decide how to analyze based on the code tag on the repository. Solidity isn't always caught correctly, but you can set the `bundle` setting default to `solidity` in the `Dashboard <https://dashboard.guardrails.io/>`_.
+
+.. note:: `View all GuardRails configuration options <https://www.guardrails.io/docs/en/configuration>`_.
+
+Scanning
+--------
+
+Once GuardRails is properly configured, whenever a pull request is created on a branch, GuardRails will start a scan in the comments. This scan may take some time, especially if you have multiple languages or multiple smart contracts. 
+
+When completed, you will see the results of the scan in the pull request:
+
+.. figure:: img/guardrails-scan.png
+
+You can see more detailed information about the issue and where it came from by clicking :guilabel:`Details` to see the scan report in the GuardRails dashboard:
+
+.. figure:: img/guardrails-details.png
+
+.. seealso::
+
+  * `GuardRails dashboard <https://dashboard.guardrails.io/>`_
+  * `GuardRails configuration <https://www.guardrails.io/docs/en/configuration>`_
+