builtin status: rename buildinfo to build-info

See: https://github.com/fish-shell/fish-shell/pull/11726#discussion_r2347389523

doc_src/cmds/status.rst

@@ -30,7 +30,7 @@ Synopsis
     status job-control CONTROL_TYPE
     status features
     status test-feature FEATURE
-    status buildinfo
+    status build-info
     status get-file FILE
     status list-files [PATH]
 
@@ -104,7 +104,7 @@ The following operations (subcommands) are available:
 **test-feature** *FEATURE*
     Returns 0 when FEATURE is enabled, 1 if it is disabled, and 2 if it is not recognized.
 
-**buildinfo**
+**build-info**
     This prints information on how fish was build - which architecture, which build system or profile was used, etc.
     This is mainly useful for debugging.