[index.md] destination docs for new Flagshipio destination (#2861)

* [index.md] destination docs for new Flagshipio destination

* [index.md] fix typo

* update syntax

Co-authored-by: stayseesong <[email protected]>

* Apply suggestions from code review

Co-authored-by: stayseesong <[email protected]>

Co-authored-by: stayseesong <[email protected]>

Author: tcgilbert

src/connections/destinations/catalog/flagshipio/index.md

@@ -0,0 +1,60 @@
+---
+title: Flagship.io Destination
+rewrite: true
+id: 626153e34fb8f47a32f8deab
+---
+
+[Flagship.io](https://www.Flagship.io/?utm_source=segmentio&utm_medium=docs&utm_campaign=partners){:target="_blank"} lets engineering teams deploy continuously and monitor the impact of features on technical infrastructure. It also enables product teams to control how features are released and how they impact user experience and business KPIs.
+
+Flagship.io maintains this destination. For any issues with the destination, [contact the Flagship Support team](mailto:[email protected]).
+
+## Getting Started
+
+{% include content/connection-modes.md %} 
+
+1. From the Destinations catalog page in the Segment App, click **Add Destination**.
+2. Search for **Flagship.io** in the Destinations Catalog, and select the **Flagship.io** destination.
+3. Choose which Source should send data to the Flagship.io destination.
+4. Go to the [Flagship.io settings interface](https://app.flagship.io/env/c92t23fode700aontbvg/settings/integrations){:target="_blank"} under **Settings > Integrations** and choose **Segment** in the dropdown. Click **Add Tool** and copy the API key displayed.
+5. Enter the **API Key** in the Flagship.io destination settings in Segment.
+
+## Supported methods
+
+Flagship.io supports the following methods as specified in the [Segment Spec](/docs/connections/spec).
+
+### Identify
+
+Send [Identify](/docs/connections/spec/identify) calls to the Flagship.io webhook. For example:
+
+```js
+analytics.identify('userId123', {
+  email: '[email protected]',
+  trait1: 1,
+  trait2: "test",
+  trait3: true
+  },    
+});
+```
+
+Segment sends Identify calls to Flagship.io as an `identify` event. The Flagship.io data engine then ingests the different traits associated to the identified user.
+
+The received traits are available in the [Flagship use case builder](https://docs.developers.flagship.io/docs/getting-started-with-flagship#4-create-your-first-campaign-on-the-platform){:target="_blank"}.
+
+
+### Group
+
+Send [Group](/docs/connections/spec/group) calls to Flagship.io webhook. The Flagship.io data engine then ingests the different traits associated to the identified group. For example:
+
+```js
+analytics.group("0e8c78ea9d97a7b8185e8632", {
+  name: "Initech",
+  industry: "Technology",
+  employees: 329,
+  plan: "enterprise",
+  "total billed": 830
+});
+```
+
+Segment sends Track calls to Flagship.io as a `group` event. The Flagship.io data engine then ingests the different traits associated to the identified user.
+
+The received traits are available in the [Flagship use case builder](https://docs.developers.flagship.io/docs/getting-started-with-flagship#4-create-your-first-campaign-on-the-platform){:target="_blank"}.