Merge pull request #50 from trilitech/palmer@functori@document-the-app

Doc: update documentation

doc/NVRAM.md

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+# NVRAM
+
+To enable verification, the ledger will retain following data in its Non-volatile memory. It will also modify data after each signing operation.
+
+Following data is saved to NVRAM:
+
+## `authorized-key`
+
+The key only key authorized to sign.
+
+It can be set, given a path and a curve, using [`AUTHORIZE_BAKING`](apdu.md#authorize_baking) and [`SETUP`](apdu.md#setup).
+A manual user validation will be required.
+And its public key will be returned.
+
+It can be unset using [`DEAUTHORIZE`](apdu.md#deauthorize).
+
+Its path can be retrieved using [`QUERY_AUTH_KEY`](apdu.md#query_auth_key) (and
+[`QUERY_AUTH_KEY_WITH_CURVE`](apdu.md#query_auth_key_with_curve) that also gives its curve)
+
+## `chain-id`
+
+The main chain id.
+
+If no chain is registered, all chains encounter will be considered as main.
+
+It can be set using [`SETUP`](apdu.md#setup) and retrieved using [`QUERY_ALL_HWM`](apdu.md#query_all_hwm).
+
+## `HWM`
+
+Two High Water Mark representing:
+ - the main chain HWM.
+ - the test chain HWM.
+
+Each HWM contains informations about the current state of the chain.
+It contains the highest level encounter and the highest round encounter for this level.
+
+The both HWM can be set using [`SETUP`](apdu.md#setup) and retrieved using [`QUERY_ALL_HWM`](apdu.md#query_all_hwm).