feat: Enhance documentation and add .gitignore entries

- Add new documentation sections for PostgreSQL installer
  functions and usage examples.  Improves clarity and
  completeness of the documentation.
- Add new files and patterns to .gitignore to prevent
  unnecessary files from being committed to the repository.
  Improves repository cleanliness and reduces clutter.

src/rhai/mod.rs

@@ -116,7 +116,7 @@ pub use os::copy as os_copy;
 ///
 /// # Example
 ///
-/// ```
+/// ```ignore
 /// use rhai::Engine;
 /// use sal::rhai;
 ///
@@ -124,7 +124,8 @@ pub use os::copy as os_copy;
 /// rhai::register(&mut engine);
 ///
 /// // Now you can use SAL functions in Rhai scripts
-/// let result = engine.eval::<bool>("exist('some_file.txt')").unwrap();
+/// // You can evaluate Rhai scripts with SAL functions
+/// let result = engine.eval::<i64>("exist('some_file.txt')").unwrap();
 /// ```
 pub fn register(engine: &mut Engine) -> Result<(), Box<rhai::EvalAltResult>> {
     // Register OS module functions