mark linear analysis interface as experimental

Author: baggepinnen

docs/src/API/linear_analysis.md

@@ -1,5 +1,8 @@
 # Linear Analysis
 
+!!! danger "Experimental"
+    The interface described here is currently experimental and at any time subject to breaking changes not respecting semantic versioning. 
+
 Linear analysis refers to the process of linearizing a nonlinear model and analysing the resulting linear dynamical system. To facilitate linear analysis, ModelingToolkitStandardLibrary provides the concept of an [`AnalysisPoint`](@ref), which can be inserted inbetween two causal blocks (such as those from the Blocks sub module). Once a model containing analysis points is built, several operations are available:
 
 - [`get_sensitivity`](@ref) get the [sensitivity function (wiki)](https://en.wikipedia.org/wiki/Sensitivity_(control_systems)), $S(s)$, as defined in the field of control theory.
@@ -94,4 +97,4 @@ Modules = [ModelingToolkitStandardLibrary.Blocks]
 Pages   = ["Blocks/analysis_points.jl"]
 Order   = [:function, :type]
 Private = false
-```
+```