Added Sensenet (crweiner#301)

Co-authored-by: Chandler Weiner <[email protected]>

CONTRIBUTING.md

@@ -137,8 +137,10 @@ If your contribution or PR is not formatted correctly, I'll let you know and giv
 - [David Ma](https://github.com/Taikon/)
 - [Khushi](https://github.com/khushijindal/)
 - [Lorenz Sieben](https://github.com/zner0L)
+- [Panagiotis Vasilopoulos](https://github.com/panos)
 - [Rohit Mathew](https://github.com/rohitjmathew)
 
+
 Disclaimer: This website is a fan and community made creation. It is not affiliated with [Hacktoberfest](https://hacktoberfest.digitalocean.com/) or any company offering swag.
 
 ![Presented by DigitalOcean, Intel, and Dev.to](img/SponsorsDarkBoxed.svg)

README.md

@@ -186,6 +186,16 @@ See [**Contributing.md**](./CONTRIBUTING.md) to see how to format your pull requ
 - **Issues**: [#hacktoberfest](https://github.com/search?&q=user%3AOperationCode+label%3Ahacktoberfest+type:issue&state=open&type=Issues)
 - **Notes**: Visit their [official post](https://github.com/OperationCode/START_HERE) for more information about how to contribute.
 
+### S
+
+#### **Sensenet**
+
+- **Swag**: Sensenet special edition socks (limit 60), 10% discount code for their [business plan](https://sensenet.com/pricing).
+- **Requirements**:
+  - 1+ merged PR
+- **How to sign up**: Complete the entry challenge by [creating a GitHub repository](https://profile.sensenet.com/?redirectToLogin) and starring [sensenet's repository](https://github.com/SenseNet/sensenet).
+- **Notes**: Check out [sensenet's Hacktoberfest page](https://hacktoberfest.sensenet.com/). Pull requests only count if they correspond to an issue found on the [dedicated board](https://github.com/orgs/SenseNet/projects/7).
+
 ### V
 
 #### **Vonage/Nexmo**
@@ -304,6 +314,14 @@ See [**Contributing.md**](./CONTRIBUTING.md) to see how to format your pull requ
 - **Issues**: [Check issues](https://github.com/meedan/check/issues?q=is%3Aissue+is%3Aopen+label%3Ahacktoberfest)
 - **Notes**: Check out [Meedan's Hacktoberfest page](https://meedan.com/hacktoberfest) for more information.
 
+#### **Sensenet**
+
+- **Requirements**:
+  - 1+ merged PR
+- **Swag**: Sensenet special edition socks (limit 60), 10% discount code for their [business plan](https://sensenet.com/pricing).
+- **How to sign up**: Complete the entry challenge by [creating a GitHub repository](https://profile.sensenet.com/?redirectToLogin) and starring [sensenet's repository](https://github.com/SenseNet/sensenet).
+- **Notes**: Check out [sensenet's Hacktoberfest page](https://hacktoberfest.sensenet.com/). Pull requests only count if they correspond to an issue found on the [dedicated board](https://github.com/orgs/SenseNet/projects/7).
+
 ### 2 or more PRs
 
 ### The Original - **DigitalOcean, Intel, and Dev** (T-shirt, stickers)