Set Up Secure Signing: edits per reviews

- Moved the LAN config tutorial to its own (draft) file to be finished later
- Mentioned dedicated signing devices such as the Ledger Nano S
- Improved the JS example's handling of secrets

content/_code-samples/secure-signing/js/signPayment.js

@@ -1,20 +1,23 @@
 'use strict'
 const RippleAPI = require('ripple-lib').RippleAPI
 
+// Load address & secret from environment variables:
+const from_address = process.env['MY_ADDRESS']
+const secret = process.env['MY_SECRET']
+
 // Can sign offline if the txJSON has all required fields
 const api = new RippleAPI()
 
-const txJSON = '{"Account":"rBXsgNkPcDN2runsvWmwxk3Lh97zdgo9za", \
-  "TransactionType":"Payment", \
-  "Destination":"rf1BiGeXwwQoi8Z2ueFYTEXSwuJYfV2Jpn", \
-  "Amount":"13000000", \
-  "Flags":2147483648, \
-  "LastLedgerSequence":7835923, \
-  "Fee":"13", \
-  "Sequence":2}'
-
-// Be careful where you store your real secret.
-const secret = 's████████████████████████████'
+const txJSON = JSON.stringify({
+  "Account": from_address,
+  "TransactionType":"Payment",
+  "Destination":"rf1BiGeXwwQoi8Z2ueFYTEXSwuJYfV2Jpn",
+  "Amount":"13000000",
+  "Flags":2147483648,
+  "LastLedgerSequence":7835923,
+  "Fee":"13",
+  "Sequence":2
+})
 
 const signed = api.sign(txJSON, secret)