Use ASCII-safe filenames for Monet & Van Gogh examples

frontend/index.html

@@ -97,7 +97,7 @@
                     <img class="example-img rounded border" src="images/examples/Titian_Bacchus_and_Ariadne.jpg" alt="" height="300">
 
                     <!-- 3. Café Terrace at Night -->
-                    <img class="example-img rounded border" src="images/examples/Vincent_van_Gogh_(1853-1890)_Caféterras_bij_nacht_(place_du_Forum)_Kröller-Müller_Museum_Otterlo_23-8-2016_13-35-40.JPG" alt="" height="300">
+                    <img class="example-img rounded border" src="images/examples/Van_Gogh_Cafe_Terrace_at_Night.jpg" alt="" height="300">
 
                     <!-- 4. The School of Athens -->
                     <img class="example-img rounded border" src="images/examples/_The_School_of_Athens__by_Raffaello_Sanzio_da_Urbino.jpg" alt="" height="300">
@@ -106,7 +106,7 @@
                     <img class="example-img rounded border" src="images/examples/Giotto_-_Scrovegni_-_-31-_-_Kiss_of_Judas.jpg" alt="" height="300">
 
                     <!-- 6. San Giorgio Maggiore at Dusk -->
-                    <img class="example-img rounded border" src="images/examples/Claude_Monet,_Saint-Georges_majeur_au_crépuscule.jpg" alt="" height="300">
+                    <img class="example-img rounded border" src="images/examples/Claude_Monet_Saint-Georges_majeur_au_crepuscule.jpg" alt="" height="300">
 
                     <!-- 7. The Last Supper -->
                     <img class="example-img rounded border" src="images/examples/The_Last_Supper_-_Leonardo_Da_Vinci_-_High_Resolution_32x16.jpg" alt="" height="300">