Excise NGM <- ODE derivation (#100)

Author: swo

docs/index.md

@@ -28,4 +28,3 @@ Let $x_i$ be the proportion of infections in group $i$ at equilibrium (i.e., so
 ## Further reading
 
 - [Linear algebra properties](linear_algebra.md) of NGMs
-- [Deriving NGMs from ODEs](ode_ngm.md)

docs/ode_ngm.md

@@ -3,7 +3,6 @@ site_name: NGM widget
 nav:
   - index.md
   - linear_algebra.md
-  - ode_ngm.md
 
 theme:
   name: "material"