Publish Nerbus source snapshot and build documentation

scripts/nerbus_sync.js

@@ -0,0 +1,13 @@
+// Read-only preflight: indexing never starts a coin daemon or mines blocks.
+const settings = require('../lib/settings');
+const Client = require('../lib/node').Client;
+const client = new Client({...settings.wallet,timeout:3000});
+client.cmd([{method:'getblockhash',params:[0]}], (err, genesis)=>{
+  if(err) { console.log('NRB node offline; index remains idle'); process.exit(0); }
+  if(genesis !== settings.block_page.genesis_block) {
+    console.error('Refusing to index an unexpected blockchain'); process.exit(1);
+  }
+  const child=require('child_process').spawn(process.execPath,['scripts/sync.js','index','update'],{stdio:'inherit'});
+  child.on('error',()=>process.exit(1));
+  child.on('exit',code=>process.exit(code==null?1:code));
+});