fix typo in Spacecraft equations

examples/Spacecraft/Spacecraft.jl

@@ -18,8 +18,8 @@
 # \begin{aligned}
 #     \dot{x} &= v_x \\
 #     \dot{y} &= v_y \\
-#     \dot{v_x} &= n^2x + 2nv_y + \dfrac{μ}{r^2} - \dfrac{μ}{r^3} (r +x) + \dfrac{u_x}{m_c} \\
-#     \dot{v_y} &= n^2y - 2nv_x - \dfrac{μ}{r^3_c}y + \dfrac{u_y}{m_c}
+#     \dot{v_x} &= n^2x + 2nv_y + \dfrac{μ}{r^2} - \dfrac{μ}{r_c^3} (r +x) + \dfrac{u_x}{m_c} \\
+#     \dot{v_y} &= n^2y - 2nv_x - \dfrac{μ}{r_c^3}y + \dfrac{u_y}{m_c}
 # \end{aligned}
 # ```
 #