Minor notebook update

docs/source/notebooks/particles-formulary-completed.ipynb

@@ -2258,7 +2258,7 @@
     "[@particle_input]: https://docs.plasmapy.org/en/stable/api/plasmapy.particles.decorators.particle_input.html\n",
     "[@check_relativistic]: https://docs.plasmapy.org/en/stable/api/plasmapy.utils.decorators.checks.check_relativistic.html#check-relativistic\n",
     "\n",
-    "Let's use both [@particle_input], [@validate_quantities], and `@check_relativistic` to write an Alfvén speed function. The formula is $$ V_A ≡ \\frac{B}{\\sqrt{μ_0 ρ}} $$ where we approximate the mass density as $ρ ≈ m_i n_i$.  "
+    "Let's use both [@particle_input], [@validate_quantities], and [@check_relativistic] to write an Alfvén speed function. The formula is $$ V_A ≡ \\frac{B}{\\sqrt{μ_0 ρ}} $$ where we approximate the mass density as $ρ ≈ m_i n_i$.  "
    ]
   },
   {