Fix umlaut rendering in LaTeX formula

Use LaTeX escape \"u instead of UTF-8 ü to fix MathJax rendering

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: mafulafunk

PITCHME.md

@@ -71,7 +71,7 @@ Relationenalgebra auf der Kommandozeile
 # Selektion
 
 > $$
-> \sigma_{\text{A}}(R) := \{ t | t \in R \wedge t \text{ erfüllt A} \}
+> \sigma_{\text{A}}(R) := \{ t | t \in R \wedge t \text{ erf\"ullt A} \}
 > $$
 
 - `SELECT * FROM Customers`