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/postgresclient/postgresclient.rs

@@ -794,7 +794,7 @@ pub fn query_opt_with_pool_params(
 /// This function sends a notification on the specified channel with the specified payload.
 ///
 /// Example:
-/// ```
+/// ```no_run
 /// use sal::postgresclient::notify;
 ///
 /// notify("my_channel", "Hello, world!").expect("Failed to send notification");
@@ -810,7 +810,7 @@ pub fn notify(channel: &str, payload: &str) -> Result<(), PostgresError> {
 /// This function sends a notification on the specified channel with the specified payload using the connection pool.
 ///
 /// Example:
-/// ```
+/// ```no_run
 /// use sal::postgresclient::notify_with_pool;
 ///
 /// notify_with_pool("my_channel", "Hello, world!").expect("Failed to send notification");