Remove conflicting style guide entry (#11665)

It was documenting the use of "startup option" for boot options
while the #boot entry is documenting the use of "boot option" instead.

wiki/src/contribute/how/documentation/style_guide.mdwn

@@ -275,18 +275,6 @@ the progressive or perfect tense.
   coordinating conjunction (usually *and* or *or*) in a series of three
   or more terms.
 
-<a id="startup-options"></a>
-
-- **startup options**
-
-  To refer to the kernel command line options that can be specified from
-  the *Boot Loader Menu*.
-
-  - *For example:*
-
-    - Adding `radeon.dpm=0` to the [[startup
-      options|/doc/first_steps/startup_options#boot_menu]].
-
 <a id="tails-greeter"></a>
 
 - **<span class="application">Tails Greeter</span>**