Add comment for zsh users in the terminal example

Bash and Zsh terminals' history works slightly different. In bash, the
current command is in the history already. In zsh, the
history command does not have the currently running command in it.  But
it does set the HISTCMD variable to the entry number for the current
command. So we can load the current command with `history "$HISTCMD"` in
zsh and apply the same sed filter to get the same result as the bash
`history | tail -n1` command.

I think it makes more sense to leave this as a comment in the current
example than to create a new example, since it otherwise works the exact
same.  I've added this to my workflow locally!

docs/examples.md

@@ -661,6 +661,8 @@ Add the following function and alias to your `.bashrc` or `.bash_profile`:
        local token=$(< ~/.ntfy_token)  # Securely read the token
        local status_icon="$([ $exit_status -eq 0 ] && echo magic_wand || echo warning)"
        local last_command=$(history | tail -n1 | sed -e 's/^[[:space:]]*[0-9]\{1,\}[[:space:]]*//' -e 's/[;&|][[:space:]]*alert$//')
+       # for zsh users, use the same sed pattern but get the history differently.
+       # local last_command=$(history "$HISTCMD" | sed -e 's/^[[:space:]]*[0-9]\{1,\}[[:space:]]*//' -e 's/[;&|][[:space:]]*alert$//')
 
        curl -s -X POST "https://n.example.dev/alerts" \
            -H "Authorization: Bearer $token" \
@@ -692,4 +694,4 @@ To test failure notifications:
 false; alert  # Always fails (exit 1)
 ls --invalid; alert  # Invalid option
 cat nonexistent_file; alert  # File not found
-```
+```