fix url in pdf (iframe)

Author: ahasverus

chapters/standards-exercice.qmd

@@ -8,7 +8,7 @@
 _Using the EML through Galaxy-Ecology_
 
 {{< fa user >}} &nbsp;**Authors:** [Yvan Le Bras](https://scholar.google.fr/citations?user=PVBOyvYAAAAJ&hl=fr) & [Olivier Norvez](https://scholar.google.fr/citations?user=0HfITX4AAAAJ&hl)<br/>
-{{< fa brands github >}} &nbsp;N/A<br/>
+{{< fa brands github >}} &nbsp;**Source:** N/A<br/>
 {{< fa globe >}} &nbsp;**Slides:** <https://biodiversitydata.github.io/chapters/standards-exercise.pdf><br/><br/>
 **License:** &nbsp;[Creative Commons Attribution 4.0](https://creativecommons.org/licenses/by/4.0/deed.en) &nbsp;{{< fa brands creative-commons >}} {{< fa brands creative-commons-by >}}
 :::
@@ -17,5 +17,5 @@ _Using the EML through Galaxy-Ecology_
 <br />
 
 <div class="container">
-  <iframe class="responsive-iframe" src="https://biodiversitydata.github.io/chapters/standards-exercise.pdf"></iframe>
+  <iframe class="responsive-iframe" src="standards-exercise.pdf"></iframe>
 </div>