manifest: optional: move lz4 to external

Move lz4 to become external module. It is not in the default manifest
anymore (through submanifests) and will need to be added if application
requires it per the docs.

Samples will be moved to the module itself.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

Author: nashif

MAINTAINERS.yml

@@ -5534,16 +5534,6 @@ West:
   labels:
     - "area: LVGL"
 
-"West project: lz4":
-  status: odd fixes
-  collaborators:
-    - parthitce
-  files:
-    - modules/lz4/
-    - samples/modules/compression/lz4/
-  labels:
-    - "area: Compression"
-
 "West project: mbedtls":
   status: maintained
   maintainers:

doc/develop/manifest/external/lz4.rst

@@ -0,0 +1,51 @@
+.. _external_module_<name>:
+
+LZ4 - Extremely fast compression
+################################
+
+Introduction
+************
+
+LZ4 is a lossless compression algorithm, providing compression speed greater
+than 500 MB/s per core, scalable with multi-core CPUs. It features an
+extremely fast decoder, with speed in multiple GB/s per core, typically
+reaching RAM speed limits on multi-core systems.
+
+Speed can be tuned dynamically by selecting an "acceleration" factor, which
+trades compression ratio for faster speed. On the other end, a high
+compression derivative, LZ4_HC, is also provided, trading CPU time for
+improved compression ratio. All versions feature the same decompression speed.
+
+LZ4 is also compatible with dictionary compression, both at API and CLI
+levels. It can ingest any input file as a dictionary, though only the final
+64KB are used. This capability can be combined
+
+
+Usage with Zephyr
+*****************
+
+To pull in lz4 as a Zephyr module, either add it as a West project in the ``west.yaml``
+file or pull it in by adding a submanifest (e.g. ``zephyr/submanifests/lz4.yaml``) file
+with the following content and run ``west update``:
+
+.. code-block:: yaml
+
+   manifest:
+     projects:
+       - name: lz4
+         url: https://github.com/zephyrproject-rtos/lz4
+         revision: main
+         path: modules/lib/lz4 # adjust the path as needed
+
+For more detailed instructions and API documentation, refer to the `lz4 documentation`_ as
+well as the provided `LZ4 examples`_.
+
+
+Reference
+*********
+
+.. lz4 documentation:
+    https://github.com/lz4/lz4/tree/dev/doc
+
+.. LZ4 examples:
+   https://github.com/zephyrproject-rtos/lz4/tree/zephyr/zephyr/samples