fix refs and doc build error

Author: vyudu

docs/src/faqs.md

@@ -311,7 +311,7 @@ Symbolics.jl before their use in Catalyst, see the discussion
 [here](https://symbolics.juliasymbolics.org/stable/manual/functions/).
 
 ## How can I turn off automatic inferring of species and parameters when using the DSL?
-This option can be set using the `@require_declaration` option inside `@reaction_network`. In this case all the species, parameters, and variables in the system must be pre-declared using one of the `@species`, `@parameters`, or `@variables` macros. For more information about what is inferred automatically and not, please see the section on [`@require_declaration`](@dsl_advanced_options_require_dec).
+This option can be set using the `@require_declaration` option inside `@reaction_network`. In this case all the species, parameters, and variables in the system must be pre-declared using one of the `@species`, `@parameters`, or `@variables` macros. For more information about what is inferred automatically and not, please see the section on [`@require_declaration`](@ref dsl_advanced_options_require_dec).
 
 ```@example faq9
 using Catalyst

docs/src/model_creation/dsl_advanced.md

@@ -278,10 +278,13 @@ In some cases it may be desirable for Catalyst to not infer species and paramete
 ```@example dsl_advanced_no_infer
 using Catalyst
 # The following case will throw an UndeclaredSymbolicError.
-rn = @reaction_network begin
+try @macroexpand @reaction_network begin
     @require_declaration
     (k1, k2), A <--> B
 end
+catch e
+    println(e.msg)
+end
 ```
 In order to avoid an error in this case all the relevant species and parameters will have to be declared.
 ```
@@ -300,7 +303,7 @@ The following cases in which the DSL would normally infer variables will all thr
 - Inferring a parameter in a reaction rate expression, as in the reaction line `k*n, A --> B`
 - Inferring a parameter in the stoichiometry of a species, as in the reaction line `k, n*A --> B`
 - Inferring a differential variable on the LHS of a coupled differential equation, as in `A` in `@equations D(A) ~ A^2`
-- Inferring an [observable](@dsl_advanced_options_observables) that is declared using `@observables`
+- Inferring an [observable](@ref dsl_advanced_options_observables) that is declared using `@observables`
 
 ## [Naming reaction networks](@id dsl_advanced_options_naming)
 Each reaction network model has a name. It can be accessed using the `nameof` function. By default, some generic name is used: