[examples] correct typo in documentation

examples/diffusion/doc/model.md

@@ -56,7 +56,7 @@ struct DiffusionModel {};
 The local residual assembles the contribution to the residual for
 all degrees of freedom associated with an element. Here, we use the
 Box method which is based on $P_1$ basis functions (piece-wise linears)
-and the degrees of freedom are on the nodes. Each node is associate with
+and the degrees of freedom are on the nodes. Each node is associated with
 exactly one sub control volume (`scv`) per element and several ($2$ in $\mathbb{R}^2$)
 sub control volume faces (`scvf`). In the local residual, we can implement the
 contribution for one `scv` (storage and source terms) or one `scvf` (flux terms).

examples/diffusion/model.hh

@@ -46,7 +46,7 @@ struct DiffusionModel {};
 // The local residual assembles the contribution to the residual for
 // all degrees of freedom associated with an element. Here, we use the
 // Box method which is based on $P_1$ basis functions (piece-wise linears)
-// and the degrees of freedom are on the nodes. Each node is associate with
+// and the degrees of freedom are on the nodes. Each node is associated with
 // exactly one sub control volume (`scv`) per element and several ($2$ in $\mathbb{R}^2$)
 // sub control volume faces (`scvf`). In the local residual, we can implement the
 // contribution for one `scv` (storage and source terms) or one `scvf` (flux terms).

examples/freeflowchannel/README.md

@@ -258,7 +258,7 @@ public:
 #### Boundary conditions
 With the following function we define the __type of boundary conditions__ depending on the location.
 Three types of boundary conditions can be specified: Dirichlet, Neumann or outflow boundary conditions. On
-Dirichlet boundaries, the values of the primary variables need to be fixed. On a Neumann boundaries,
+Dirichlet boundaries, the values of the primary variables need to be fixed. On Neumann boundaries,
 values for derivatives need to be fixed. Outflow conditions set a gradient of zero in normal direction towards the boundary
 for the respective primary variables (excluding pressure).
 When Dirichlet conditions are set for the pressure, the velocity gradient

examples/freeflowchannel/problem.hh

@@ -60,7 +60,7 @@ public:
     // #### Boundary conditions
     // With the following function we define the __type of boundary conditions__ depending on the location.
     // Three types of boundary conditions can be specified: Dirichlet, Neumann or outflow boundary conditions. On
-    // Dirichlet boundaries, the values of the primary variables need to be fixed. On a Neumann boundaries,
+    // Dirichlet boundaries, the values of the primary variables need to be fixed. On Neumann boundaries,
     // values for derivatives need to be fixed. Outflow conditions set a gradient of zero in normal direction towards the boundary
     // for the respective primary variables (excluding pressure).
     // When Dirichlet conditions are set for the pressure, the velocity gradient