Replace one flat bread image (#229)

We used the same image several times. This adds a new different image.

book/bread-types/bread-types.tex

@@ -21,11 +21,10 @@ Flatbread is probably the simplest sourdough bread to make.
 To make a flatbread no oven is required; all you need is a stove.
 
 \begin{figure}[!htb]
-  \includegraphics[width=\textwidth]{sourdough-stove}
-  \caption[Einkorn done on open fire]{An einkorn flatbread made directly over
-      fire. This is part of a video where I~was trying to reproduce sourdough
-      recipes of our ancestors. I~called the recipe ``cave bread''. Some
-      viewers pointed out that probably not all our ancestors lived in caves.}
+  \includegraphics[width=\textwidth]{flat-breads-selection}
+  \caption[Flatbread selection with different flours]{An assorted selection of
+      different flatbreads made with sourdough. From left to right:
+      Wheat tortilla, rye, spelt and corn.}%
 \end{figure}
 
 This type of bread is super simple to make as you can skip