virtual-media: rename file to match conventions

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I0726148815e1cbcd97977fc086d14991e3dcdf7a
diff --git a/designs/VirtualMedia.md b/designs/virtual-media.md
similarity index 100%
rename from designs/VirtualMedia.md
rename to designs/virtual-media.md