docs(content): add Keine Tashi UTAU project page

Add bilingual (EN/FR) content pages documenting the BSUP01 Keine Tashi
UTAU vocal library project, including character information, vocal
library specifications, download links, and usage licence.

Also add .small-img CSS class for floating images in content pages.

app/assets/css/main.css

@@ -4,3 +4,12 @@
 @import './tailwind.css';
 
 @source "../../../content/**/*";
+
+.small-img {
+  max-width: 30rem;
+  max-height: 30rem;
+  width: auto;
+  height: auto;
+  float: right;
+  margin: 2rem;
+}