[PATCH v3 3/3] crypto: add examples to CRYPTO_PUBLIC_KEYS

[Marco Felsch <m.felsch@pengutronix.de>]

It's pretty easy to get the documentation for the __ENV__ handling
wrong. Therefore add a few examples which are currently supported.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
---
Changelog:
v3:
- new patch

 crypto/Kconfig | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/crypto/Kconfig b/crypto/Kconfig
index 14728be4aa91..97836a75ce5a 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -148,6 +148,24 @@ config CRYPTO_PUBLIC_KEYS
 	  corresponding value in the environment variable VAR_NAME for both
 	  public key paths/URIs as well as key name hints.
 
+	  Examples specified directly:
+
+	  - CONFIG_CRYPTO_PUBLIC_KEYS="pkcs11:object=foo"
+	  - CONFIG_CRYPTO_PUBLIC_KEYS="myhint:pkcs11:object=foo"
+	  - CONFIG_CRYPTO_PUBLIC_KEYS="myhint:pkcs11:object=foo /foobar/baz.der"
+	  - CONFIG_CRYPTO_PUBLIC_KEYS="myhint:pkcs11:object=foo myotherhint:/foobar/baz.der"
+
+	  Example specified indirectly by two environment variables:
+
+	  - myhint="myhint"
+	  - myname="pkcs11:object=foo" (.der could be used too)
+	  - CONFIG_CRYPTO_PUBLIC_KEYS="__ENV__myhint:__ENV__myname"
+
+	  Example specified indirectly by a single environment variable:
+
+	  - mykey="myhint:pkcs11:object=foo" (.der could be used too)
+	  - CONFIG_CRYPTO_PUBLIC_KEYS="__ENV__mykey"
+
 config CRYPTO_KEYSTORE
 	bool "Keystore"
 	help
-- 
2.39.5