Update the Tizen lighting app description

* update tizen app call to use the full path
* describe regeneration of author certificates

examples/lighting-app/tizen/README.md

@@ -32,9 +32,32 @@ and security profile using the commands described below. Change password and
 author data as needed.
 
 ```sh
-tizen certificate --alias=CHIP --name=CHIP [email protected] --password=chiptizen
+$TIZEN_SDK_ROOT/tools/ide/bin/tizen certificate --alias=CHIP --name=CHIP [email protected] --password=chiptizen
+$TIZEN_SDK_ROOT/tools/ide/bin/tizen security-profiles add --active --name=CHIP --author=$HOME/tizen-sdk-data/keystore/author/author.p12 --password=chiptizen
+```
+
+This is only _one-time action_. To regenerate the author certificate and
+security profile, you have to remove files from the `$HOME` directory using
+specified commands:
+
+```sh
+rm -r \
+	$HOME/tizen-sdk-data \
+	$HOME/.tizen-cli-config \
+	$HOME/.secretsdb
+```
 
-tizen security-profiles add --active --name=CHIP --author=$HOME/tizen-sdk-data/keystore/author/author.p12 --password=chiptizen
+After that, normally call scripts to generate the author certificate and
+security profile mentioned previously.
+
+### Important
+
+Regenerating the author certificate and security profile makes it necessary to
+remove the previously installed Tizen app. You can't reinstall an application on
+the Tizen device with a different certificate.
+
+```sh
+pkgcmd -u -n org.tizen.matter.example.lighting
 ```
 
 ## Packaging APP