fix euler's identity (#220)

content/notes/CJK + Latex Support (测试).md

@@ -17,7 +17,7 @@ $$f(x) = \int_{-\infty}^\infty
     f\hat(\xi),e^{2 \pi i \xi x}
     \,d\xi$$
 	
-Inline math also works with single dollar signs `$...$`. For example, Euler's identity but inline: $e^{i\pi} = 0$
+Inline math also works with single dollar signs `$...$`. For example, Euler's identity but inline: $e^{i\pi} = -1$
 
 Aligned equations work quite well: