Additional explanation of small_constant in docstring

Author: SKopecz

src/mprk.jl

@@ -134,7 +134,8 @@ You can optionally choose the linear solver to be used by passing an
 algorithm from [LinearSolve.jl](https://github.com/SciML/LinearSolve.jl)
 as keyword argument `linsolve`.
 You can also choose the parameter `small_constant` which is added to all Patankar-weight denominators 
-to avoid divisions by zero.
+to avoid divisions by zero. You can pass a value explicitly, otherwise `small_constant` is set to
+`floatmin` of the floating point type used.
 
 ## References
 
@@ -345,7 +346,8 @@ You can optionally choose the linear solver to be used by passing an
 algorithm from [LinearSolve.jl](https://github.com/SciML/LinearSolve.jl)
 as keyword argument `linsolve`.
 You can also choose the parameter `small_constant` which is added to all Patankar-weight denominators 
-to avoid divisions by zero.
+to avoid divisions by zero. You can pass a value explicitly, otherwise `small_constant` is set to
+`floatmin` of the floating point type used.
 
 ## References
 
@@ -726,7 +728,8 @@ You can optionally choose the linear solver to be used by passing an
 algorithm from [LinearSolve.jl](https://github.com/SciML/LinearSolve.jl)
 as keyword argument `linsolve`.
 You can also choose the parameter `small_constant` which is added to all Patankar-weight denominators 
-to avoid divisions by zero.
+to avoid divisions by zero. You can pass a value explicitly, otherwise `small_constant` is set to
+`floatmin` of the floating point type used.
 
 ## References
 
@@ -825,7 +828,8 @@ You can optionally choose the linear solver to be used by passing an
 algorithm from [LinearSolve.jl](https://github.com/SciML/LinearSolve.jl)
 as keyword argument `linsolve`.
 You can also choose the parameter `small_constant` which is added to all Patankar-weight denominators 
-to avoid divisions by zero.
+to avoid divisions by zero. You can pass a value explicitly, otherwise `small_constant` is set to
+`floatmin` of the floating point type used.
 
 ## References
 

src/sspmprk.jl

@@ -22,7 +22,8 @@ You can optionally choose the linear solver to be used by passing an
 algorithm from [LinearSolve.jl](https://github.com/SciML/LinearSolve.jl)
 as keyword argument `linsolve`.
 You can also choose the parameter `small_constant` which is added to all Patankar-weight denominators 
-to avoid divisions by zero.
+to avoid divisions by zero. You can pass a value explicitly, otherwise `small_constant` is set to
+`floatmin` of the floating point type used.
 
 ## References
 
@@ -408,7 +409,8 @@ You can optionally choose the linear solver to be used by passing an
 algorithm from [LinearSolve.jl](https://github.com/SciML/LinearSolve.jl)
 as keyword argument `linsolve`.
 You can also choose the parameter `small_constant` which is added to all Patankar-weight denominators 
-to avoid divisions by zero.
+to avoid divisions by zero. You can pass a value explicitly, otherwise `small_constant` is set to
+`floatmin` of the floating point type used.
 
 ## References