fix: replaced floating relative URLs with ones affixed to root

[alryaz]

What it fixes

Fixes navigation issues after opening pages from external websites

Source of the issue

Forward slash character (/) gets appended every time a page is visited on the hacs.xyz website. Therefore clicking URLs with no forward slash in the beginning will cause their target to be appended to the end of the current URL.

Edit: To be clear, this only occurs when the starting URL (https://hacs.xyz/docs/publish/start in the example below) is visited directly due to Javascript code not appending a trailing slash whenever navigation is performed.

Steps to reproduce

1. Do one of the following:
   • From GitHub:
     1. Navigate to HACS Default GitHub Home Page
     2. Click the first link displayed in the README file (https://hacs.xyz/docs/publish/start)
   • From browser window:
     1. Enter the following URL into the address bar: https://hacs.xyz/docs/publish/start
     2. Press the Enter key
   • From this pull request:
     1. Follow the following URL: https://hacs.xyz/docs/publish/start
2. Notice how the URL gets rewritten: https://hacs.xyz/docs/publish/start -> https://hacs.xyz/docs/publish/start/
   (a forward slash gets appended)
3. Click any of the URLs under the General Requirements link (Integration requirements, Plugin requirements, etc.)
4. Reach a 404: Page not found