Add setExternalPlugin command

doc/ethapp.asc

@@ -20,6 +20,9 @@ Application version 1.5.0 - 25th of September 2020
   - Add SIGN ETH EIP 712  
   - Add GET ETH2 PUBLIC KEY
 
+## 1.6.3
+  - Add SET EXTERNAL PLUGIN
+
 ## About
 
 This application describes the APDU messages interface to communicate with the Ethereum application. 
@@ -237,6 +240,39 @@ signed by the following secp256k1 public key 0482bbf2f34f367b2e5bc21847b6566f21f
 
 None
 
+
+### SET EXTERNAL PLUGIN
+
+#### Description
+
+This commands provides the name of a plugin that should be called to interpret contract data in the following transaction signing command.
+
+It shall be run immediately before performing a transaction involving a contract supported by this plugin to display the proper information to the user if necessary.
+
+The function returns an error sw (0x6984) if the plugin requested is not installed on the device, 0x9000 otherwise.
+
+#### Coding
+
+'Command'
+
+[width="80%"]
+|==============================================================================================================================
+| *CLA* | *INS*  | *P1*               | *P2*       | *Lc*     | *Le*
+|   E0  |   12   |  00   |   00       | variable   | 00
+|==============================================================================================================================
+
+'Input data'
+
+[width="80%"]
+|==============================================================================================================================
+| *Description*                                                                     | *Length*
+| Plugin name                                                                       | variable
+|==============================================================================================================================
+
+'Output data'
+
+None
+
 ### GET APP CONFIGURATION
 
 #### Description