Rerendered the encryption-at-rest_solution diagram to include

the envelope->record rename.

(also fixed up a couple of white backgrounds (envelope + gear icons) that showed up when view in dark mode)

Signed-off-by: kwall <[email protected]>

Author: k-wall

README.md

@@ -36,4 +36,10 @@ You can then run the site with this command (don't close the terminal once you'v
 
 ```bash
 bundle exec jekyll serve
-```
+```
+
+# Excalidraw images
+
+Some content such as the use-cases include diagrams drawn in Excalidraw.  Browsers can't handle the format natively, so instead, in addition to
+preserving the `.excalidraw` we also export a transparent `.png` for inclusion in the content.
+