fix: update cargo toml keywords (#4)

Author: hashemix

Cargo.toml

@@ -6,7 +6,7 @@ categories = ["data-structures", "parser-implementations", "parsing"]
 description = "Type-safe implementation of the Model Context Protocol in Rust, designed to reduce errors and accelerate development with powerful utilities."
 repository = "https://github.com/rust-mcp-stack/rust-mcp-schema"
 documentation = "https://docs.rs/rust-mcp-schema"
-keywords = ["rust-mcp-stack", "model", "content", "protocol", "schema"]
+keywords = ["rust-mcp-stack", "model", "context", "protocol", "schema"]
 license = "MIT"
 edition = "2021"