Updated readme for 0.5.0 release [Last PR before releasing 0.5.0]

[imarios]

Hey @adelbertc and @OlivierBlanvillain. I would love to have your take on my proposed changes for the landing page. Thanks!

Here is the link to my branch in case you want to see how it renders:
https://github.com/imarios/frameless/tree/update_readme_0.5

[adelbertc]

LGTM! 👍

[codecov-io]

Codecov Report

Merging #249 into master will decrease coverage by 0.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #249      +/-   ##
==========================================
- Coverage   96.56%   96.45%   -0.12%     
==========================================
  Files          51       51              
  Lines         874      874              
  Branches       11       11              
==========================================
- Hits          844      843       -1     
- Misses         30       31       +1

Impacted Files	Coverage Δ
...c/main/scala/frameless/TypedDatasetForwarded.scala	71.42% <0%> (-2.86%)	⬇️
...ataset/src/main/scala/frameless/TypedEncoder.scala	100% <0%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 968492a...3d20c51. Read the comment docs.

[imarios]

Hey @OlivierBlanvillain! this will be the last PR in 0.5.0, do you have few minutes to give it a quick look?

[OlivierBlanvillain]

👍