fd: update page (#15038)

Co-authored-by: Wiktor Perskawiec <git@spageektti.cc>

pages/common/fd.md

@@ -8,13 +8,13 @@
 
 `fd "{{string|regex}}"`
 
-- Find files that begin with `foo`:
+- Find files that begin with a specific string:
 
-`fd "^foo"`
+`fd "{{^string}}"`
 
 - Find files with a specific extension:
 
-`fd --extension txt`
+`fd --extension {{txt}}`
 
 - Find files in a specific directory: