RPC - Add bls fromsecret

Related to dashpay/dash#2841

_includes/devdoc/dash-core/rpcs/quick-reference.md

@@ -178,7 +178,7 @@ These RPCs are all Dash-specific and not found in Bitcoin Core
 
 {% autocrossref %}
 
-* [BLS][rpc bls]: {{summary_bls}} {{DASH_NEW0_13_0}}
+* [BLS][rpc bls]: {{summary_bls}} {{DASH_UPDATED0_14_0}}
 * [ProTx][rpc protx]: {{summary_proTx}} {{DASH_UPDATED0_14_0}}
 
 {% endautocrossref %}

_includes/devdoc/dash-core/rpcs/rpcs/bls.md

@@ -61,6 +61,57 @@ Result:
 }
 {% endhighlight %}
 
+{% endautocrossref %}
+
+###### BLS<!--noref--> FromSecret
+<!-- no subhead-links here -->
+
+{% autocrossref %}
+
+The `bls<!--noref--> fromsecret` RPC parses a BLS secret key and returns the secret/public key pair.
+
+*Parameter #1---secret key*
+
+{% itemplate ntpd1 %}
+- n: "`secret`"
+  t: "string (hex)"
+  p: "Required<br>(exactly 1)"
+  d: "The BLS secret key"
+{% enditemplate %}
+
+*Result---the secret/public key pair*
+
+{% itemplate ntpd1 %}
+- n: "`result`"
+  t: "object"
+  p: "Required<br>(exactly 1)"
+  d: "BLS key pair"
+
+- n: "→<br>`secret`"
+  t: "string (hex)"
+  p: "Required<br>(exactly 1)"
+  d: "A BLS secret key"
+
+- n: "→<br>`public`"
+  t: "string (hex)"
+  p: "Required<br>(exactly 1)"
+  d: "A BLS public key"
+{% enditemplate %}
+
+*Example from Dash Core 0.14.0*
+
+{% highlight bash %}
+dash-cli -testnet bls fromsecret 52f35cd3d977a505485f2474e7e71ef3f60f859603d72ad6b0fa7f7bd163e144
+{% endhighlight %}
+
+Result:
+{% highlight json %}
+{
+  "secret": "52f35cd3d977a505485f2474e7e71ef3f60f859603d72ad6b0fa7f7bd163e144",
+  "public": "885d01d746c3e4d2093b0975de2d8c1f3e5a2c3e8fdaaed929f86fc9fbb278a095248163c101a2456650b415776b7990"
+}
+{% endhighlight %}
+
 *See also: none*
 
 {% endautocrossref %}

_includes/layout/base/rpc-table.html

@@ -305,7 +305,7 @@ th.tg-sort-header::-moz-selection { background:transparent; }th.tg-sort-header::
     <td class="tg-b7b8">Evolution</td>
     <td class="tg-b7b8"><a href="#bls">BLS</a></td>
     <td class="tg-dzk6">Y</td>
-    <td class="tg-dzk6">Added in 0.13.0</td>
+    <td class="tg-dzk6">Updated in 0.14.0</td>
   </tr>
   <tr>
     <td class="tg-yw4l">Evolution</td>