Introduce Harrow explanation

_includes/navigation.html

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 <ul class="side-nav">
-  <li><a href="https://www.harrow.io/hosted-capistrano-for-teams/?utm_source=CAP&utm_medium=BAN&utm_term=00001&utm_campaign=00004&utm_campaign=CAP_BAN_00001_00004#hosted-capistrano-for-teams" title="Harrow | Seamless collaboration for software teams"><span class="label label-important">New</span> Hosted Capistrano for Teams</a></li>
+  <h5>Hosted Capistrano</h5>
+  <li><a href="https://www.harrow.io/hosted-capistrano-for-teams/?utm_source=CAP&utm_medium=BAN&utm_term=00001&utm_campaign=00004&utm_campaign=CAP_BAN_00001_00004#hosted-capistrano-for-teams" title="Harrow | Seamless collaboration for software teams">Try The New Cloud Capistrano</a></li>
+  <li><a href="/documentation/harrow">Learn more</a></li>
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documentation/harrow/index.markdown

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+---
+title: What is Harrow?
+layout: default
+---
+
+### Harrow is a web-based platform for continuous integration and deployment built by the Capistrano team.
+
+There are many continuous integration tools in the world already, Harrow is
+ours. It is designed to "feel" familiar to Capistrano users.
+
+![Harrow, web-based Capistrano](/images/capistrano-logo-harrow-logo-c-primary-darker-w640.png)
+
+Although Harrow is designed to work well for Capistrano-style use-cases, it is
+by no means limited to only being used for Capistrano, or even for deployment.
+
+Some of the features which make Harrow ideal for automating tools such as
+Capistrano;
+
+* A discrete concept of scripts and environments, allowing reuse of scripts in
+  different settings using different configurations.
+* A pure JSON-HAL API allowing integrations and tools
+* Powerful triggers and notifications allowing the construction of pipelines
+  starting with git changes
+
+Harrow, much like Capistrano can also be used to:
+
+* To automate common tasks in software teams.
+* To drive infrastructure provisioning tools such as *chef-solo*, *Ansible* or similar.
+
+Again, like Capistrano; Harrow is also *very* scriptable, and can be integrated
+with any other software to form part of a larger tool.
+
+#### How To Use Harrow
+
+1. Sign up for an account at <https://www.app.harrow.io/#/a/signin>
+2. Connect your Git repository using our setup wizard
+3. Choose "Capistrano" as the project template
+
+#### What does it cost, and how does that affect Capistrano
+
+Harrow has very low pricing (<https://harrow.io/pricing/>), for comparison with
+other continuous integration tools we have customers who have cut their monthly
+outgoing by a factor of 5 or more.
+
+For individual users it's feee to use for ever. To work with collaborators in
+your projects paid plans start at just $29/mo.
+
+Capistrano is unaffected by Harrow. Capistrano will remain liberally licensed
+(currently MIT) and will include discrete hooks offering Harrow to users
+without being intrusive.