create_manpage_completions: include deroff.py directly

Enables the next commit.

cmake/Install.cmake

@@ -136,7 +136,7 @@ install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/user_doc/man/man1/
         PATTERN "*.1"
         PATTERN ${CONDEMNED_PAGE} EXCLUDE)
 
-install(PROGRAMS share/tools/create_manpage_completions.py share/tools/deroff.py
+install(PROGRAMS share/tools/create_manpage_completions.py
         DESTINATION ${rel_datadir}/fish/tools/)
 
 install(DIRECTORY share/tools/web_config

share/functions/fish_update_completions.fish

@@ -23,7 +23,7 @@ function fish_update_completions --description "Update man-page based completion
         $python $update_args
     end
     __fish_data_with_directory tools \
-        'create_manpage_completions\.py|deroff\.py' \
+        'create_manpage_completions\.py' \
         __fish_update_completions $argv
     __fish_with_status functions --erase __fish_update_completions
 end