improve docs

Author: hexaeder

docs/src/data_structure.md

@@ -1,14 +1,12 @@
 # Data Structure
 
 A [`Network`](@ref) contains a list of vertex and edge models along with a graph.
-
 However, in tight numerical loops, it will never access these lists of models directly.
 Instead, the network maintains an internal representation that tracks all symbolic indices, defining the precise ordering of states and parameters in a flat array representation. To optimize performance, especially for heterogeneous networks, the network employs specialized data structures that batch identical models together.
 
 This disconnect between the explicit lists and the internal data structures
 can be confusing.
 
-
 ## Flat Parameter and State Arrays
 
 The vertex and edge models may contain metadata, such as initial values for states and parameters.
@@ -66,3 +64,6 @@ nothing #hide
     nw = Network(complete_graph(3), [v1,v2,v1], e; dealias=true)
     nw[VIndex(1)] === nw[VIndex(3)] # neither of them === v1
     ```
+
+## Extracting `Network`-object from Containers
+`NetworkDynamics.jl` provides a [`extract_nw`](@ref) function, to get a reference to the wrapped `Network` object from different containers, such as solution objects or integrator objects.

docs/src/metadata.md

@@ -28,7 +28,7 @@ Special cases for symbol metadata are:
 - `default`: Stores default values for states/parameters. In initialization, those are considered fixed.
 - `guess`: Stores a guess for a state/parameter which needs to solved during initialization ("free" variables).
 - `bounds`: Store bounds for variables/parameters
-- `init`: Stores the solution of the "free" variables during initialization.
+- `init`: Stores the solution of the "free" variables, this is rarely set manual but instead when calling [`initialize_component`](@ref).
 
 Fore those, there are special functions `has_*`, `get_*` and `set_*!`. See [Per Symbol Metadata API](@ref).
 

src/callbacks.jl

@@ -69,7 +69,7 @@ Creates a callback condition for a [`ComponentCallback`].
        - `ctx.model`: a referenc to the ocmponent model
        - `ctx.vidx`/`ctx.eidx`: The index of the vertex/edge model.
        - `ctx.src`/`ctx.dst`: src and dst indices (only for edge models).
-       - `ctx.integrator`: The integrator object.
+       - `ctx.integrator`: The integrator object. Use [`extract_nw`](@ref) to obtain the network.
        - `ctx.t=ctx.integrator.t`: The current simulation time.
 - `sym`: A vector or tuple of symbols, which represent **states** (**excluding**
   inputs, outputs, observed) of the component model. Determines, which states will