docs(readme): update

README.md

@@ -1,6 +1,6 @@
 # td [![Go Reference](https://pkg.go.dev/badge/github.com/gotd/td.svg)](https://pkg.go.dev/github.com/gotd/td/telegram) [![codecov](https://codecov.io/gh/gotd/td/branch/main/graph/badge.svg?token=shR5PXG7Ds)](https://codecov.io/gh/gotd/td)
 
-Telegram client and MTProto implementation in go.
+Fast Telegram client fully in go.
 
 * [Security policy](.github/SECURITY.md)
 * [User support and dev chat](.github/SUPPORT.md)
@@ -12,32 +12,40 @@ Before using this library, read [How Not To Get Banned](https://github.com/gotd/
 
 ## Status
 
-Work in progress. Only go1.16 is supported and no backward compatibility is provided.
+Work is still in progress, but basic functionality were tested in production and works fine.
+Only go1.16 is supported and no backward compatibility is provided for now.
 
-Goal of this project is to implement Telegram client while
-providing building blocks for the other client or even server
-implementation without performance bottlenecks.
+Goal of this project is to implement stable, performant and safe client for Telegram in go while
+providing simple and convenient API.
 
 This project is fully non-commercial and not affiliated with any commercial organization
 (including Telegram LLC).
 
 ## Features
 
 * Full MTProto 2.0 implementation in go
-* Code for Telegram types generated by `./cmd/gotdgen` (based on [gotd/tl](https://github.com/gotd/tl) parser)
-* Embedded [official documentation](https://core.telegram.org/schema)
+* Code for Telegram types generated by `./cmd/gotdgen` (based on [gotd/tl](https://github.com/gotd/tl) parser) with embedded [official documentation](https://core.telegram.org/schema)
 * Pluggable session storage
 * Automatic re-connects with keepalive
 * Vendored Telegram public keys that are kept up-to-date
-* End-to-end and unit testing, fuzzing
+* Rigorously tested
+  * End-to-end with real Telegram server in CI
+  * End-to-End with gotd Telegram server (in go)
+  * Lots of unit testing
+  * Fuzzing
+  * 24/7 canary bot in production that tests reconnects, update handling, memory leaks and performance
 * No runtime reflection overhead
-* Secure PRNG used for crypto
+* [Conforms](https://github.com/gotd/td/issues/155) to [Security guidelines](https://core.telegram.org/mtproto/security_guidelines) for Telegram client software developers
+  * Secure PRNG used for crypto
+  * Replay attack protection
 * 2FA support
 * MTProxy support
-* Connection pooling
-* Helpers for uploads and downloads
-* CDN support
-* Automatic DC migration and redirect handling
+* Multiple helpers that hide complexity of raw Telegram API
+  * [uploads](https://pkg.go.dev/github.com/gotd/td/telegram/uploader) for big and small files with multiple streams for single file and progress reporting
+  * [downloads](https://pkg.go.dev/github.com/gotd/td/telegram/downloader) with CDN support, also multiple streams
+  * [messages](https://pkg.go.dev/github.com/gotd/td/telegram/message) with various convenience builders and text styling support
+* CDN support with connection pooling
+* Automatic datacenter migration and redirects handling
 
 ## Example