Add note on float test (#318)

The float test is not super reliable - this adds some comments on when
it can work and when it does not.

book/troubleshooting/misc.tex

@@ -345,6 +345,17 @@ made with such a starter. The flavor when taking a bite
 is incredible. It nicely plays with soups as well. Just take
 a bit of this bread and dip it in your soup.
 
+\subsection{Why does my starter not float after using the float test?}
+The float test may not reliably determine your starter's readiness for dough
+inoculation. While it's effective for wheat-based doughs, where ample gas gets
+trapped in the gluten matrix, it's less reliable for non-wheat doughs. In non-
+wheat doughs, the gas generated during fermentation tends to escape, causing
+the starter to likely sink.
+
+For more accurate assessments of your starter's readiness, watch for bubbles
+at the container's edge and consider its aroma. A mature starter should emit a
+mildly sour scent without being overly pungent.
+
 \section{Dough}
 \subsection{Should I~autolyse my dough?}