doc: fix typo in debugger.md

Use apostrophe for possessive.

PR-URL: #36066
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>

Author: Trott

doc/api/debugger.md

@@ -115,7 +115,7 @@ To begin watching an expression, type `watch('my_expression')`. The command
 * `setBreakpoint()`, `sb()`: Set breakpoint on current line
 * `setBreakpoint(line)`, `sb(line)`: Set breakpoint on specific line
 * `setBreakpoint('fn()')`, `sb(...)`: Set breakpoint on a first statement in
-  functions body
+  function's body
 * `setBreakpoint('script.js', 1)`, `sb(...)`: Set breakpoint on first line of
   `script.js`
 * `setBreakpoint('script.js', 1, 'num < 4')`, `sb(...)`: Set conditional