Move the examples of labeled functions to StdLabels (#9976)

In the old days, the interfaces of the labeled modules
(ArrayLabels, BytesLabels, ListLabels, StringLabels)
started with short examples of labelings.

Now, the interfaces of the non-labeled modules
(Array, Bytes, List, String) are automatically generated
from the interfaces of the labeled modules.  As a side effect,
the interfaces of Array, Bytes, List and String also start
with short examples of labelings, which is somewhat strange.

This commit reorganizes the documentation as follows:
- The documentation of the StdLabels module is expanded, and includes
  the examples of labeled functions previously scattered in
  ArrayLabels, BytesLabels, ListLabels, StringLabels.
- Array, Bytes, List, String and their labeled counterparts
  briefly mention the labeled modules and point to StdLabels,
  but no longer contain examples.

1 files changed, 3 insertions, 11 deletions

diff --git a/stdlib/string.mli b/stdlib/string.mli
index a3a87baf1c..2f2d7f1b72 100644
--- a/stdlib/string.mli
+++ b/stdlib/string.mli
@@ -73,17 +73,9 @@ v}
     default until OCaml 4.05. Starting with 4.06, the compatibility
     mode is opt-in; we intend to remove the option in the future.
 
-
-  The labeled version of this module, {!StringLabels}, is intended to be used
-  through {!StdLabels} which replaces {!Array}, {!Bytes}, {!List} and
-  {!String} with their labeled counterparts
-
-  For example:
-  {[
-     open StdLabels
-
-     let to_upper = String.map ~f:Char.uppercase_ascii
-  ]} *)
+    The labeled version of this module can be used as described in the
+    {!StdLabels} module.
+*)
 
 (** {1:strings Strings} *)