fix(cli): add CSS selector examples to scrape --selector help text

Fixes bounty issue #1378

The --selector flag for the scrape command now includes practical examples
of common CSS selectors, making it easier for users unfamiliar with CSS
to understand how to use the flag effectively.

Author: factorydroid

cortex-cli/src/scrape_cmd.rs

@@ -77,6 +77,13 @@ pub struct ScrapeCommand {
     pub no_links: bool,
 
     /// CSS selector to extract specific content.
+    ///
+    /// Examples:
+    ///   - 'div.main' - Select divs with class "main"
+    ///   - '#content' - Select element with id "content"
+    ///   - 'article p' - Select all paragraphs inside articles
+    ///   - 'h1, h2, h3' - Select all h1, h2, and h3 headings
+    ///   - '.post-content' - Select elements with class "post-content"
     #[arg(long, value_name = "SELECTOR")]
     pub selector: Option<String>,