feat(*): update filter to add a greeting header

Author: hishamhm

Cargo.lock

@@ -13,4 +13,3 @@ proxy-wasm = "0.2"
 log = "0.4"
 serde-json-wasm = "0.5.0"
 serde = { version = "*", features = ["derive"] }
-chrono = "0.4"

Cargo.toml

@@ -3,9 +3,17 @@ Proxy-Wasm Rust Filter Template
 
 This repository contains a [Proxy-Wasm](https://github.com/proxy-wasm/spec)
 filter that can be used as a reference to quickly start implementing new
-filters. The filter implements the entrypoints and function calls supported by
-WasmX. Please refer to [WasmX docs](https://github.com/Kong/ngx_wasm_module/blob/main/docs/PROXY_WASM.md#supported-entrypoints)
-for the list of supported entrypoints.
+filters in Rust.
+
+This is a "hello-world" type filter performing a minimal operation and showing
+the basics of filter configuration: it simply adds a new header `X-Greeting`
+to a proxied response. You can pass the filter a JSON configuration in the
+format `{ "my_greeting": "Howdy!" }` to change the value of the injected
+header.
+
+Please refer to [WasmX
+docs](https://github.com/Kong/ngx_wasm_module/blob/main/docs/PROXY_WASM.md#supported-entrypoints)
+for the list of supported functions and entrypoints.
 
 Requirements
 ============