Update topology_complex_plane.html

Author: jcponce

content/topology_complex_plane.html

@@ -288,7 +288,7 @@ <h2>Topological space</h2>
 https://www.youtube.com/watch?v=pSjahcOnJvU
                         -->
 
-                    A set $S$ is <em id="open-set">open</em> if for every $z\in S,$ exits
+                    A set $S$ is <em id="open-set">open</em> if for every $z\in S,$ exists
                     $\varepsilon&gt;0$ such that
                     $$B_{\varepsilon}(z)\subset S.$$
                     That is, $\text{Int } S= S.$