Add PiXHost API to readme

PiXhost like imgur is a image hosting service and is free to all users. Some people who have slightly more graphical content that gets rejected at imgur switch to PiXhost because it has more lenient rules. It also has an API that is not known.

From their website:

"Welcome to the PiXhost API!
You can use this API to upload images, covers or galleries.
The following image formats are supported: image/gif, image/png, image/jpeg. Maximum image size is 10 MB.
In case you have any ideas, questions or issues, feel free to contact us at: admin@pixhost.org.
Old API users: We recently enforced https, please update your scripts."

README.md

@@ -476,6 +476,7 @@ API | Description | Auth | HTTPS | Link |
 | Gfycat | Jiffier GIFs | `OAuth` | Yes | [Go!](https://developers.gfycat.com/api/) |
 | Giphy | Get all your gifs | No | Yes | [Go!](https://github.com/Giphy/GiphyAPI) |
 | Imgur | Images | `OAuth` | Yes | [Go!](https://apidocs.imgur.com/) |
+| PiXhost | Upload images, photos, galleries | | No | Yes | [Go!](https://pixhost.org/api/index.html)
 | PlaceKitten | Resizable kitten placeholder images | No | Yes | [Go!](https://placekitten.com/) |
 | ScreenShotLayer | URL 2 Image | No | Yes | [Go!](https://screenshotlayer.com) |
 | Unsplash | Photography | `OAuth` | Yes | [Go!](https://unsplash.com/developers) |