Package docstring: more peaceful README introduction

[fonsp]

Hello! 👋

#39093 is great! This PR styles the banner ("Displaying contents of readme found at ...") differently:

Before:

help?> DifferentialEquations
search: DifferentialEquations

  No docstring found for module DifferentialEquations.

  Exported names
  ≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡

  @derivatives, @ode_def, @ode_def_all, @ode_def_bare, 
  ... (manually truncated)

  Displaying contents of readme found at /Users/ian/.julia/packages/DifferentialEquations/HSWeG/README.md
  ≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡

  DifferentialEquations.jl
  ≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡

  (Image: Join the chat at https://gitter.im/JuliaDiffEq/Lobby) (https://gitter.im/JuliaDiffEq/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) (Image:
  Build Status) (https://github.com/SciML/DifferentialEquations.jl/actions?query=workflow%3ACI) (Image: Stable) (http://diffeq.sciml.ai/stable/) (Image: Dev) (http://diffeq.sciml.ai/dev/)
  (Image: DOI) (https://zenodo.org/badge/latestdoi/58516043)

  This is a suite for numerically solving differential equations written in Julia and available for use in Julia, Python, and R. The purpose of this package is to supply efficient Julia
  implementations of solvers for various differential equations. Equations within the realm of this package include:

    •  Discrete equations (function maps, discrete stochastic (Gillespie/Markov) simulations)

    •  Ordinary differential equations (ODEs)

After:

help?> DifferentialEquations
search: DifferentialEquations

  No docstring found for module DifferentialEquations.

  Exported names
  ≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡

  @derivatives, @ode_def, @ode_def_all, @ode_def_bare, 
  ... (manually truncated)

  ────────────────────────────────────────────────────────────────────────────

  Package description from README.md:

  DifferentialEquations.jl
  ≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡

  (Image: Join the chat at https://gitter.im/JuliaDiffEq/Lobby) (https://gitter.im/JuliaDiffEq/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) (Image:
  Build Status) (https://github.com/SciML/DifferentialEquations.jl/actions?query=workflow%3ACI) (Image: Stable) (http://diffeq.sciml.ai/stable/) (Image: Dev) (http://diffeq.sciml.ai/dev/)
  (Image: DOI) (https://zenodo.org/badge/latestdoi/58516043)

  This is a suite for numerically solving differential equations written in Julia and available for use in Julia, Python, and R. The purpose of this package is to supply efficient Julia
  implementations of solvers for various differential equations. Equations within the realm of this package include:

    •  Discrete equations (function maps, discrete stochastic (Gillespie/Markov) simulations)

    •  Ordinary differential equations (ODEs)

I think this makes it a bit less technical (the word "Displaying" and the long filename), and it improves the reading flow.