add jathan's and my DebConf20 presentations

Signed-off-by: Holger Levsen <holger@layer-acht.org>

_data/presentations.yml

+- title: Reproducing Bullseye in practice
+  presented_by: Holger Levsen
+  event:
+    url: https://debconf20.debconf.org/talks/49-reproducing-bullseye-in-practice/
+    name: DebConf20
+    date: 2020-8-27
+    location: online
+  video:
+    url: https://meetings-archive.debian.net/pub/debian-meetings/2020/DebConf20/49-reproducing-bullseye-in-practice.webm
+  slides: https://reproducible-builds.org/_lfs/presentations/2020-08-27-Reproducing-bullseye-in-practice/
+
+- title: Construcciones reproducibles en Debian (Debian Reproducible Builds): Un camino verificable desde el origen hasta el binario
+  presented_by: Jonathan Bustillos
+  event:
+    url: https://debconf20.debconf.org/talks/81-construcciones-reproducibles-en-debian-debian-reproducible-builds-un-camino-verificable-desde-el-origen-hasta-el-binario/
+    name: DebConf20
+    date: 2020-8-24
+    location: online
+  video:
+    url: https://meetings-archive.debian.net/pub/debian-meetings/2020/DebConf20/81-construcciones-reproducibles-en-debian-debian-reproducible-builds-un-camino-verificable-desde-el-origen-hasta-el-binario.webm
+
 - title: Reproducible Toolchains For the Win!
   presented_by: Vagrant Cascadian
   event: