Provides Mattermost notifications when a chat is initiated.
## Installation
1. Get the archive with the plugin sources. You can download it from the [official site](https://mibew.org/plugins#mibew-mattermost) or build the plugin from sources.
2. Extract the downloaded plugin archive file.
3. Put files of the plugins to the `<Mibew root>/plugins` folder.
4. Obtain a webhook key from Mattermost:
a. Go to you Mattermost instance, open "Integrations" in the settings, find and enter "Incoming WebHooks app".
b. Click on "Add Incoming Webhook". Fill out the form and click on "Save".
c. Copy the value of the "Webhook URL".
5. Add plugin's config to plugins structure like below.
```yaml
plugins:
"Mibew:Mattermost": # Plugin's configurations are described below