docs: replace Firefox with Zen Browser

docs/git.org

@@ -41,7 +41,7 @@
 
 #+begin_src conf-unix
 [web]
-	browser = firefox
+	browser = zen-browser
 #+end_src
 
 ** Aliases

docs/hyprland.org

@@ -362,7 +362,7 @@ It is sort of the general menu for my keybindings.
 #+name: apps-submap
 | Modifiers | Key | Action | Argument          | Submap |
 |-----------+-----+--------+-------------------+--------|
-|           | b   | exec   | =firefox=           | reset  |
+|           | b   | exec   | =zen-browser=       | reset  |
 | SHIFT     | b   | exec   | =qutebrowser=       | reset  |
 |           | d   | exec   | =vesktop=           | reset  |
 |           | e   | exec   | =emacsclient -c -n= | reset  |

docs/shell.org

@@ -119,9 +119,9 @@ It’s always nice to have the =BROWSER= variable available in case you
 want to do stuff with scripts and your default browser.
 
 #+name: browser
-| Variable | Value   |
-|----------+---------|
-| =BROWSER=  | =firefox= |
+| Variable | Value       |
+|----------+-------------|
+| =BROWSER=  | =zen-browser= |
 
 #+begin_src sh
 <<export-variables(browser)>>