docs: updates for mattermost service

README.md

@@ -57,6 +57,7 @@ as message. And most of all this serves as a swiss army knife sort of tool which
 - *Slack*
 - *Telegram*
 - *Pushover*
+- *Mattermost*
 
 
 ## Install
@@ -114,13 +115,13 @@ NAME:
    PingMe - Send message to multiple platforms
 
 USAGE:
-   pingme [global options] command [command options] [arguments...]
+   main [global options] command [command options] [arguments...]
 
 DESCRIPTION:
    PingMe is a CLI tool which provides the ability to send messages or alerts to multiple
    messaging platforms and also email, everything is configurable via environment
    variables and command line switches.Currently supported platforms include Slack, Telegram,
-   RocketChat, Discord, Microsoft Teams and email address.
+   RocketChat, Discord, Pushover, Mattermost, Microsoft Teams and email address.
 
 COMMANDS:
    telegram    Send message to telegram
@@ -130,6 +131,7 @@ COMMANDS:
    teams       Send message to microsoft teams
    pushover    Send message to pushover
    email       Send an email
+   mattermost  Send message to mattermost
    help, h     Shows a list of commands or help for one command
 
 GLOBAL OPTIONS: