Update documentation for gravity wave diagnostics

Correct typo in `diagnostics.md` and add detailed explanation of `eps` parameter usage in `gravity_wave.md`.

Author: ray-chew

docs/src/diagnostics.md

@@ -209,10 +209,6 @@ were computed differently for `EquilMoistModel` and `NonEquilMoistModel`.
 In `ClimaAtmos`, we define some helper functions to produce error messages, so
 the above code can be written as
 ```julia
-compute_relative_humidity!(out, state, cache, time) =
-    compute_relative_humidity!(out, state, cache, time, cache.atmos.moisture_model)
-compute_relative_humidity!(_, _, _, _, model::T) where {T} =
-    error_diagnostic_variable("relative_humidity", model)
 
 function compute_relative_humidity!(
     out,
@@ -228,6 +224,11 @@ function compute_relative_humidity!(
         out .= TD.relative_humidity.(thermo_params, cache.ᶜts)
     end
 end
+
+compute_relative_humidity!(out, state, cache, time) =
+    compute_relative_humidity!(out, state, cache, time, cache.atmos.moisture_model)
+compute_relative_humidity!(_, _, _, _, model::T) where {T} =
+    error_diagnostic_variable("relative_humidity", model)
 ```
 
 ### The `ClimaAtmos` `DiagnosticVariable`s

docs/src/gravity_wave.md

@@ -165,8 +165,9 @@ Similar to the base flux calculation but for the 3D fields, we computed ``N`` an
 ^f N[k]^2 = \frac{g}{^f T[k]} * ( ^f \overline{\frac{dT}{dz}}[k] + \frac{g}{cp}),
 ```
 ```math
-^f V_{\tau}[k] = \max(\epsilon_0, - V[k] \cdot \frac{\tau}{|\tau|}).
+^f V_{\tau}[k] = \max(\epsilon_0, - V[k] \cdot \frac{\tau}{|\tau|}),
 ```
+where where ``\epsilon_0`` denotes a measure of floating-point precision.
 
 Let ``L_1 = L_0 * \max(0.5, \min(2.0, 1.0-samp*V_\tau*d^2V_{\tau}/N^2))`` where ``samp=1.0`` is the correction for coarse sampling of ``d^2V/dz^2``, and
 ```math