doc: update Readme.md about how to use kernel quilt release

Signed-off-by: Lili Li <[email protected]>

Author: lilili-kernel

Readme.md

@@ -1,7 +1,75 @@
-This repository contains Intel's Linux LTS quilt releases. 
+### Introduction
 
-GPG Signed Releases
--------------------
+This repository contains Intel's Linux LTS and mainline kernel quilt releases.
+
+Kernel quilt release 'patches' folder include a quilt series file and all kernel patches mentioned in the series file.\
+kernel patches are grouped by feature, example:
+
+```
+    #series file for v6.12.40 linux kernel
+    # d90ecb2b1308b Linux 6.12.40
+    #sriov
+    0001-drm-i915-mtl-Add-C10-table-for-HDMI-Clock-25175.sriov
+    0002-drm-i915-mtl-Copy-c10-phy-pll-sw-state-from-master-t.sriov
+    0003-drm-i915-guc-Define-MAX_DWORDS-for-CTB-HXG-Message.sriov
+    0004-drm-i915-call-taint_for_CI-on-FLR-failure.sriov
+    ...
+    #security
+    0001-mei-bus-add-api-to-query-capabilities-of-ME-clien.security
+    ...
+```
+
+### How to use quilt release
+
+Step 1: clone and checkout quilt release, lts-v6.12.40-linux-250728T040815Z as example:
+
+```
+         $ git clone https://github.com/intel/linux-intel-quilt.git linux-intel-quilt
+         $ cd linux-intel-quilt
+         $ git checkout lts-v6.12.40-linux-250728T040815Z -b my/v6.12.40
+```
+
+Step 2: use 'cat patches/series |head -n2' to get the base kernel version and HEAD, lts-v6.12.40-linux-250728T040815Z as example:
+
+```
+         $ cat patches/series |head -n2
+         # Series file for v6.12.40 linux kernel
+         # d90ecb2b1308b Linux 6.12.40
+```
+
+Step 3: clone base kernel from community [stable](https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git) or [mainline](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git). Continue use above tag as example:
+
+```
+         $ cd ..
+         $ git clone https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git kernel-src
+         $ cd kernel-src
+         $ git checkout v6.12.40 -b my/v6.12.40
+         $ cp -r ../linux-intel-quilt/patches .
+```
+
+Step 4: use quilt or git quiltimport to apply kernel patches to your branch.
+
+quilt example:
+```
+        $ quilt push -a
+```
+
+git quiltimport example:
+```
+        $ git quiltimport
+```
+
+Step 5: modify your kernel configuration with 'make menuconfig' or copy from your existing configuration and 'make bindeb-pkg' to build this kernel.
+
+
+Note: If you don't want apply all the patches, you can also modify the series file to remove patches/features before applying.
+
+### Reference kernel overlay repository
+
+You can also use our kernel overlay release to build the kernel instead of apply quilt series by yourself.\
+You can find reference kernel configuration, kernel patch series and build scripts from this [linux kernel overlay release repository](https://github.com/intel/linux-kernel-overlay).
+
+### GPG Signed Releases
 
 i) Check if a release tag is GPG-signed or not