docs: update README and index page

PRs: #719 #720

Co-authored-by: Steve Francis <steve.francis@siderolabs.com>
Signed-off-by: Andrey Smirnov <andrey.smirnov@talos-systems.com>
Signed-off-by: Steve Francis <steve.francis@siderolabs.com>

README.md

@@ -1,5 +1,9 @@
 # Sidero
 
+Kubernetes Bare Metal Lifecycle Management.
+Sidero Metal provides lightweight, composable tools that can be used to create bare-metal Talos + Kubernetes clusters.
+ Sidero Metal is an open source project from [Sidero Labs](https://www.SideroLabs.com).
+
 ## Documentation
 
 Visit the project [site](https://www.sidero.dev).

website/content/docs/v0.5/index.md

@@ -8,8 +8,8 @@ Welcome to the Sidero documentation.
 
 - Slack: Join our [slack channel](https://slack.dev.talos-systems.io)
 - Forum: [community](https://groups.google.com/a/SideroLabs.com/forum/#!forum/community)
-- Twitter: [@talossystems](https://twitter.com/SideroLabs)
-- Email: [info@talos-systems.com](mailto:info@SideroLabs.com)
+- Twitter: [@SideroLabs](https://twitter.com/SideroLabs)
+- Email: [info@SideroLabs.com](mailto:info@SideroLabs.com)
 
 If you're interested in this project and would like to help in engineering efforts, or have general usage questions, we are happy to have you!
 We hold a weekly meeting that all audiences are welcome to attend.