move parts into doc

Author: findmyway

README.md

@@ -4,31 +4,6 @@
 [![Coverage](https://codecov.io/gh/JuliaReinforcementLearning/Trajectories.jl/branch/main/graph/badge.svg)](https://codecov.io/gh/JuliaReinforcementLearning/Trajectories.jl)
 [![PkgEval](https://JuliaCI.github.io/NanosoldierReports/pkgeval_badges/T/Trajectories.svg)](https://JuliaCI.github.io/NanosoldierReports/pkgeval_badges/report.html)
 
-## Core Concepts
-
-### Install & Usage
-
-```julia
-julia> ] add Trajectories
-
-julia> using Trajectories
-```
-
-### Trace
-
-```julia
-Trace(data)
-```
-
-A wrapper of arbitrary container. Generally we assume the `data` is an
-`AbstractVector` like object. When an `AbstractArray` is given, we view it as a
-vector of sub-arrays along the last dimension.
-
-```julia
-t = Trace([1,2,3])
-```
-
-
 ## Design
 
 ```