fix broken link and add logging example (FuelLabs#3767)

README.md

@@ -51,4 +51,4 @@ cargo run --bin forc -- --help
 
 We welcome contributions to Sway!
 
-Please see the [Contributing To Sway](https://fuellabs.github.io/sway/master/reference/contributing_to_sway.html) section of the Sway book for guidelines and instructions to help you get started.
+Please see the [Contributing To Sway](https://fuellabs.github.io/sway/master/book/reference/contributing_to_sway.html) section of the Sway book for guidelines and instructions to help you get started.

docs/book/src/basics/comments_and_logging.md

@@ -37,6 +37,17 @@ fn main() {
 
 The `logging` library provides a generic `log` function that can be imported using `use std::logging::log` and used to log variables of any type. Each call to `log` appends a `receipt` to the list of receipts. There are two types of receipts that a `log` can generate: `Log` and `LogData`.
 
+```sway
+fn log_values(){
+  // Generates a Log receipt
+  log(42);
+
+  // Generates a LogData receipt
+  let string = "sway";
+  log(string);
+}
+```
+
 ### `Log` Receipt
 
 The `Log` receipt is generated for _non-reference_ types, namely `bool`, `u8`, `u16`, `u32`, and `u64`. For example, logging an integer variable `x` that holds the value `42` using `log(x)` may generate the following receipt: