Update documentation

docs/options.md

@@ -61,6 +61,8 @@ This dropdown allows you to select how ballots are transferred during surplus tr
 * Unweighted inclusive Gregory: During surplus transfers, a transfer value is calculated as the candidate's excess votes divided by the candidate's ballot papers. Ballot weights are set to the transfer value. Transferred votes are credited in parcels to avoid excessive rounding.
 * Wright STV: Same as weighted inclusive Gregory, but when a candidate is excluded, the count is reset from the beginning (minus the excluded candidate).
 
+Note that, in each of these options, all a candidate's ballot papers are examined during a surplus transfer. The practice used in some rules (e.g. ERS97) where ballot papers are divided into transferable and non-transferable papers, and only transferable papers further examined, is not currently supported.
+
 Note that, when unweighted inclusive Gregory surplus transfers are used, ballot weights are always represented internally as fractions, while candidate totals are represented according to the *Numbers* option.
 
 Other surplus transfer methods, such as exclusive Gregory (‘last bundle’) or non-fractional transfers (e.g. random sample) are not recommended and not supported.

html/index.html

@@ -45,6 +45,7 @@
 				</select>
 			</label>
 			<button id="btnAdvancedOptions" onclick="clickAdvancedOptions()">Show advanced options</button>
+			<a href="https://yingtongli.me/blog/2020/12/24/pyrcv2.html">Information and instructions</a>
 		</div>
 		
 		<div id="divAdvancedOptions" style="display: none;">