fix typo

lec02.tex

@@ -19,7 +19,7 @@ Let $k$ be a field.
 \end{bsp}
 
 \begin{satz}[]
-    For a $k$-scheme $X$ the following are equvialent:
+    For a $k$-scheme $X$ the following are equivalent:
     \begin{enumerate}[(i)]
         \item $X$ is geometrically reduced
         \item for every reduced $k$-scheme $Y$, the fibre product $X \times_k Y$ is reduced.