add vault

closes #17 (closed)

doc/config.md

 # Ğcli config 
 
 Some Ğcli commands require to have an address configured (for example to get account balance), some require to have a secret configured (to sign extrinsics).
-Ğcli allows to save what you want in a config file and to overwrite parts in command line arguments. Example:
+Ğcli allows to save the address you want in a config file and to overwrite parts in command line arguments. Example:
 
 ```sh
-# save Alice secret to config file
-cargo run -- -S predefined -s Alice config save
+# save Alice address to config file
+gcli -S predefined -s Alice config save
 
 # show config 
-cargo run -- config show
+gcli config show
 # [stdout]
 # Ğcli config
 # duniter endpoint ws://localhost:9944
 # indexer endpoint http://localhost:4350/graphql
-# address 5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY (secret defined)
+# address 5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY
 
 # use different address in command line
-cargo run -- --address 5Fxune7f71ZbpP2FoY3mhYcmM596Erhv1gRue4nsPwkxMR4n config show
+gcli --address 5Fxune7f71ZbpP2FoY3mhYcmM596Erhv1gRue4nsPwkxMR4n config show
 # [stdout]
 # Ğcli config
 # duniter endpoint ws://localhost:9944
 # indexer endpoint http://localhost:4350/graphql
-# address 5Fxune7f71ZbpP2FoY3mhYcmM596Erhv1gRue4nsPwkxMR4n (no secret)
+# address 5Fxune7f71ZbpP2FoY3mhYcmM596Erhv1gRue4nsPwkxMR4n
 ```
 
-You can see that if a secret is defined, the associated address is used, but if an other address is given, the secret is silenced.
+This also applies to rpc endpoint config (`--url`) or indexer config (`--indexer`).
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+
+## Using password encrypted vault
+
+For convenience, default accounts are hardcoded in Ğcli without needing a password:
+
+```sh
+# when Alice address is stored in config file
+gcli account transfer 1 5Fxune7f71ZbpP2FoY3mhYcmM596Erhv1gRue4nsPwkxMR4n
+# no need for password to sign transaction
+```
+
+but in general usage, you want to store your secret in the local vault. This goes like this:
+
+```sh
+# list available keys in the vault
+gcli vault list
+# [stdout]
+# available keys:
+# 5DfhGyQdFobKM8NsWvEeAKk5EQQgYe9AydgJ7rMB6E1EqRzV
+
+# add a new secret to the vault
+gcli vault import
+# [stdout]
+# Mnemonic: <enter mnemonic> 
+# Password: <enter password>
+```
+
+After saving your secret to the vault, you will be able to unlock it with the password:
+
+```sh
+gcli account transfer 123 5Fxune7f71ZbpP2FoY3mhYcmM596Erhv1gRue4nsPwkxMR4n
+# [stdout]
+# Enter password to unlock account 5DfhGyQdFobKM8NsWvEeAKk5EQQgYe9AydgJ7rMB6E1EqRzV
+# Password: <enter password>
+# transaction submitted to the network, waiting 6 seconds...
+# transfered 1.23 ĞD (5DfhGyQdFobKM8NsWvEeAKk5EQQgYe9AydgJ7rMB6E1EqRzV → 5Fxune7f71ZbpP2FoY3mhYcmM596Erhv1gRue4nsPwkxMR4n)
+```
+
+You can display the secret files location:
+
+```sh
+gcli vault where
+# [stdout]
+# /home/hugo/.local/share/gcli
+```
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