Beautify example showcase site URLs (#12348)

# Objective

The current example showcase site URLs have white-space and caps in them
which looks ugly as an URL.

Fixes https://github.com/bevyengine/bevy-website/issues/736

## Solution

To fix this the example showcase tool now makes the category used for
the site sections lowercase, separated by a hyphen rather than
white-space, and without parentheses.

---------

Co-authored-by: Rob Parrett <robparrett@gmail.com>
Co-authored-by: vero <email@atlasdostal.com>

tools/example-showcase/src/main.rs

@@ -464,7 +464,19 @@ header_message = \"Examples (WebGL2)\"
                 if !to_show.wasm {
                     continue;
                 }
-                let category_path = root_path.join(&to_show.category);
+
+                // This beautifys the path
+                // to make it a good looking URL
+                // rather than having weird whitespace
+                // and other characters that don't
+                // work well in a URL path.
+                let category_path = root_path.join(
+                    &to_show
+                        .category
+                        .replace(['(', ')'], "")
+                        .replace(' ', "-")
+                        .to_lowercase(),
+                );
 
                 if !categories.contains_key(&to_show.category) {
                     let _ = fs::create_dir_all(&category_path);
@@ -500,6 +512,10 @@ title = \"{}\"
 template = \"example{}.html\"
 weight = {}
 description = \"{}\"
+# This creates redirection pages
+# for the old URLs which used
+# uppercase letters and whitespace.
+aliases = [\"/examples{}/{}/{}\"]
 
 [extra]
 technical_name = \"{}\"
@@ -516,6 +532,12 @@ header_message = \"Examples ({})\"
                             },
                             categories.get(&to_show.category).unwrap(),
                             to_show.description.replace('"', "'"),
+                            match api {
+                                WebApi::Webgpu => "-webgpu",
+                                WebApi::Webgl2 => "",
+                            },
+                            to_show.category,
+                            &to_show.technical_name.replace('_', "-"),
                             &to_show.technical_name.replace('_', "-"),
                             match api {
                                 WebApi::Webgpu => "-webgpu",