Updating Oh My Zsh shop URLs (#7619)

* Updating Oh My Zsh shop URLs

Linking directly to the Oh My Zsh inventory vs the top-level store with non-OMZ items.

* Updating link to Oh My Zsh products in the install script

* Updating link to Oh My Zsh shop products in the upgrade script

* Getting rid of 't-' in shirts for now

tools/install.sh

@@ -105,7 +105,7 @@ main() {
   echo ''
   echo 'p.s. Follow us at https://twitter.com/ohmyzsh.'
   echo ''
-  echo 'p.p.s. Get stickers and t-shirts at https://shop.planetargon.com.'
+  echo 'p.p.s. Get stickers, shirts, and coffee mugs at https://shop.planetargon.com/collections/oh-my-zsh.'
   echo ''
   printf "${NORMAL}"
   env zsh -l