[Buildroot] [git commit branch/2018.05.x] package/linux-headers: add help text for manual header selection

[Peter Korsgaard]

commit: https://git.buildroot.net/buildroot/commit/?id=b8b6e0e833ec17c4486d95c86a1c565befbbce18
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/2018.05.x

Add kconfig help text that explains how to manually specify an
official Linux version to use for the kernel headers.

Signed-off-by: Mark Corbin <mark.corbin at embecosm.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
(cherry picked from commit 3beba26d7657840c07bf014e33f9e80b6f1b09af)
Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
---
 package/linux-headers/Config.in.host | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/package/linux-headers/Config.in.host b/package/linux-headers/Config.in.host
index ef3ccce348..502042256e 100644
--- a/package/linux-headers/Config.in.host
+++ b/package/linux-headers/Config.in.host
@@ -73,6 +73,14 @@ config BR2_KERNEL_HEADERS_4_16
 
 config BR2_KERNEL_HEADERS_VERSION
 	bool "Manually specified Linux version"
+	help
+	  This option allows you to use a specific official version from
+	  kernel.org, like 2.6.x, 2.6.x.y, 3.x.y, ...
+
+	  Note: you cannot use this option to select a _longterm_ 2.6
+	  kernel, because these kernels are not located at the standard
+	  URL at kernel.org. Instead, select "Custom tarball" and
+	  specify the right URL directly.
 
 endchoice