[libc] Fix typo in libc fullbuild mode doc (#85204)

"In order to" is more appropriate.

libc/docs/fullbuild_mode.rst

@@ -6,7 +6,7 @@ Fullbuild Mode
 
 The *fullbuild* mode of LLVM's libc is the mode in which it is to be used as
 the only libc (as opposed to the :ref:`overlay_mode` in which it is used along
-with the system libc.) In to order use it as the only libc, one will have to
+with the system libc.) In order to use it as the only libc, one will have to
 build and install not only the static archives like ``libc.a`` from LLVM's libc,
 but also the start-up objects like ``crt1.o`` and the public headers.