Enable automatic hyphenation (set lang metadata)

Change-Id: I5c885d3043a27766e2b1dfec05703347d0f45d3d
diff --git a/inst/rmarkdown/templates/posterdown_ids/resources/template.html b/inst/rmarkdown/templates/posterdown_ids/resources/template.html
index de99327..01556c9 100644
--- a/inst/rmarkdown/templates/posterdown_ids/resources/template.html
+++ b/inst/rmarkdown/templates/posterdown_ids/resources/template.html
@@ -61,6 +61,7 @@
 padding-bottom: 2.54cm;
 text-align: justify;
 font-family: $if(font_family)$$font_family$$else$Fira Sans$endif$;
+hyphens: auto;
 }
 .poster_wrap {
 width: $if(poster_width)$$poster_width$$else$827mm$endif$;