### Why is this Change Important & Necessary?

The documentation concerning Routes was outdated. The old syntax of
`@Route(...)` is deprecated and in fact will no longer work with the
recent update to the Route object we include from Symfony in [PR
#12935](Submitty/Submitty#12935).

### New Additions

Instances of `@Route(...)` have been replaced with `#[Route(...)]` to
match what will be expected from developers when writing PHP code.

### Screenshots

#### Before
1. Controller page:
<img width="1620" height="951" alt="image"
src="https://github.com/user-attachments/assets/56bd84aa-f0b3-4d36-830d-c4eb84db370f"
/>

2. Excerpt from Router page:
<img width="1650" height="951" alt="image"
src="https://github.com/user-attachments/assets/3e0d70db-0517-4689-b3ce-fa35475c18db"
/>

3. Excerpt from Routes and Responses page:
<img width="1650" height="951" alt="image"
src="https://github.com/user-attachments/assets/2b041778-698f-41f2-9bff-2cdad0b06277"
/>


#### After
1. Updated Controller page:
<img width="1620" height="951" alt="image"
src="https://github.com/user-attachments/assets/ad1a7dd4-530d-4cbf-b62c-98f81536a37a"
/>

2. Updated Router page:
<img width="1650" height="951" alt="image"
src="https://github.com/user-attachments/assets/6f1cf287-8bc8-4818-b9e3-eb25bd490e3c"
/>

3. Updated Routes and Responses page:
<img width="1650" height="951" alt="image"
src="https://github.com/user-attachments/assets/a7fe9db4-3feb-4ed6-819f-0099068da5b5"
/>


### Other information
Unfortunately, the markdown renderer thinks the #[Route(...)] syntax is
a comment due to the leading #. If at some point GitHub pages updates
their markdown renderer to allow for PHP 8 syntax highlighting then the
Routes will appear correctly as uncommented.
Example of how it is now:
<img width="437" height="319" alt="image"
src="https://github.com/user-attachments/assets/5daab045-878e-4ef2-a165-faca83feeea4"
/>
Here is how it actually looks in the code:
<img width="503" height="321" alt="image"
src="https://github.com/user-attachments/assets/87e875d8-c2cd-4ee8-82fe-5ad8107531a5"
/>

Notice how the routes are not italicized. 

This is not really a big deal but it kind of annoys me that the routes
look like they are comments. However, I think that is better than
rendering these code blocks as plain text or a different language than
php (both of which would make the route appear 'correctly').

Also, the example given of UserController on the Controller / View pages
is code that no longer exists in the submitty codebase. It is still a
good example of how to write our php code but at some point we should
probably update the example to use real code.