doc: usage: add usage details for reset cmd

Add usage details for reset command.

Signed-off-by: Igor Opaniuk <igor.opaniuk@foundries.io>
diff --git a/doc/usage/index.rst b/doc/usage/index.rst
index b64cfe4..528b3c7 100644
--- a/doc/usage/index.rst
+++ b/doc/usage/index.rst
@@ -40,3 +40,4 @@
    sbi
    true
    scp03
+   reset