Fix typo in constrained_edges.jl docs (#113)

docs/src/literate_tutorials/constrained_edges.jl

@@ -45,7 +45,7 @@ ax1 = Axis(fig[1, 1], xlabel="x", ylabel=L"y",
     title="(a): Unconstrained", titlealign=:left,
     width=300, height=300)
 ax2 = Axis(fig[1, 2], xlabel="x", ylabel=L"y",
-    title="(b): Unconstrained", titlealign=:left,
+    title="(b): Constrained", titlealign=:left,
     width=300, height=300)
 triplot!(ax1, tri)
 triplot!(ax2, cons_tri, show_constrained_edges = true)
@@ -65,4 +65,4 @@ get_interior_segments(cons_tri)
 # but in the case of a triangulation with constrained 
 # boundaries, it will also include the boundary segments
 # whereas `get_interior_segments` will not; this is 
-# demonstrated in the later tutorials. 
+# demonstrated in the later tutorials.