talks: Add event link

src/talks.rec

@@ -29,6 +29,7 @@ video-url: https://media.libreplanet.org/u/libreplanet/m/the-surreptitious-assau
 link: /talks/sapsf.pdf Slides
 link: /projects/sapsf/plain/sapsf.bib Bibliography
 link: /projects/sapsf/ Source Code
+event-link: https://libreplanet.org/2017
 
 
 id: cs4m
@@ -52,6 +53,7 @@ abstract: Words like "wizardry" and "incantation" have long been used to describ
 + and nontechnical alike.
 link: /talks/cs4m.pdf Slides
 link: /projects/cs4m/ Source Code
+event-link: https://libreplanet.org/2019
 
 
 id: ethics-void
@@ -75,6 +77,7 @@ abstract: Many communities have widely adopted codes of ethics governing the
 video-url: https://media.libreplanet.org/u/libreplanet/m/the-ethics-void/
 link: /talks/ethics-void.pdf Slides
 link: /projects/ethics-void/ Source Code
+event-link: https://libreplanet.org/2018
 
 
 id: online-freedom
@@ -102,3 +105,4 @@ abstract: Imagine a world where surveillance is the default and users must
 video-url: https://media.libreplanet.org/u/libreplanet/m/restore-online-freedom/
 link: https://media.libreplanet.org/u/libreplanet/m/restore-online-freedom-14bf/ Slides
 link: /projects/online-freedom/ Source Code
+event-link: https://libreplanet.org/2016

src/talks.sh

@@ -61,6 +61,7 @@ abstract()
   date=$( talk-field "$id" date )
   abstract=$( talk-field "$id" abstract )
   url=$( talk-field "$id" video-url || echo "#$id" )
+  event_link=$( talk-field "$id" event-link )
   links=$( talk-field "$id" link )
 
   local abstract_html
@@ -86,7 +87,8 @@ abstract()
 
   $abstract_html
 
-  <p class="date">Presented on $date at $location.</p>
+  <p class="date">Presented on $date at
+    <a href="$event_link">$location</a>.</p>
 </article>
 EOF
 }