Fix tabs and numbering

wiki/src/doc/first_steps/startup_options.mdwn

@@ -23,21 +23,21 @@ starting Tails.</p>
 
 </div>
 
-1.  To add a boot option, press <span class="keycap">Tab</span> when the
-    <span class="application">Boot Loader Menu</span> appears. A list of boot options
-    appears at the bottom of the screen.
+1. To add a boot option, press <span class="keycap">Tab</span> when the
+   <span class="application">Boot Loader Menu</span> appears. A list of boot options
+   appears at the bottom of the screen.
 
-[[!img boot-menu-with-options.png link=no alt="Black screen with Tails
-artwork. Boot Loader Menu with two options 'Tails' and 'Tails (Troubleshooting Mode)'.
-At the bottom, a list of options ending with 'vsyscall=none quiet_'"]]
+   [[!img boot-menu-with-options.png link=no alt="Black screen with Tails
+   artwork. Boot Loader Menu with two options 'Tails' and 'Tails (Troubleshooting Mode)'.
+   At the bottom, a list of options ending with 'vsyscall=none quiet_'"]]
 
-2.  Press <span class="keycap">Space</span>, and type the boot option that you
-    want to add.
+2. Press <span class="keycap">Space</span>, and type the boot option that you
+   want to add.
 
-3.  If you want to add more than one boot option, type them one after the
-    other, and separate them by a <span class="keycap">Space</span>.
+3. If you want to add more than one boot option, type them one after the
+   other, and separate them by a <span class="keycap">Space</span>.
 
-4.  Then press <span class="keycap">Enter</span> to start Tails.
+4. Then press <span class="keycap">Enter</span> to start Tails.
 
 <a id="greeter"></a>
 <a id="tails_greeter"></a>