update description of blocks rescan

static/admin/dmt/blocks-rescan/blocks-rescan.html

@@ -1,7 +1,7 @@
 <div id="blocks-rescan">
   <h1>BLOCKS RESCAN</h1>
 
-  <div class="box-context">Force the Tracker to rescan a range of blocks.</div>
+  <div class="box-context">Force the Tracker to rescan a small range of blocks.</div>
 
   <div class="row box-main">
     <div id="blocks-rescan-form" class="box fullwidth">

static/admin/dmt/welcome/welcome.html

@@ -26,7 +26,7 @@
   <span class="item-descr">Check if a transaction is found in a block or in the mempool of your full node.</span>
 
   <span class="item">BLOCKS RESCAN</span>
-  <span class="item-descr">Rescan the transactions confirmed by the blocks in a given range.</span>
+  <span class="item-descr">Force the Tracker to rescan a small range of blocks.<br/>For large rescans you should prefer XPUB or address rescans.</span>
 
   <span class="items-category ">HELP</span>