bump version to 0.3.0; update README;

Signed-off-by: jmic <jmic@users.noreply.github.com>

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "altcha-lib-rs"
-version = "0.2.0"
+version = "0.3.0"
 edition = "2021"
 authors = ["jmic <jmic@users.noreply.github.com>"]
 description = "Community implementation of the Altcha library in Rust for your own server application to create and validate challenges and responses."

README.md

@@ -12,6 +12,7 @@ For more information about ALTCHA <https://altcha.org/docs>
 - Generates and validates self-hosted challenges
 - Expiring challenges option
 - Supports the algorithms SHA256, SHA384, SHA512, and SHA1 (via optional feature flag)
+- With v0.3, enforces delimited salt to prevent replay attacks; see https://altcha.org/security-advisory/
 
 **Not part of this library:** 
 - Methods to call ALTCHA's spam filter API