Fix typos <noupdate>

src/statistical-and-mathematical-methods-for-ai/sections/_linear_algebra.tex

@@ -324,9 +324,9 @@ we can prove that $\forall c \in \mathbb{R} \smallsetminus \{0\}:$ $c\vec{x}$ is
 \end{theorem}
 
 
-\begin{theorem}[Spectral theorem] \marginnote{Spectral theorem}
+\begin{theorem}[Spectral theorem] \label{th:spectral_theorem} \marginnote{Spectral theorem}
     Given a symmetric matrix $\matr{A} \in \mathbb{R}^{n \times n}$.
-    Its eigenvectors form a orthonormal basis and its eigenvalues are all in $\mathbb{R}$.
+    Its eigenvectors form an orthonormal basis and its eigenvalues are all in $\mathbb{R}$.
 \end{theorem}