Improve https://ocaml.org/learn/portability.html page

[nibble0101]

Issue description

When you navigate to learn/portability page, you will see a couple of tables which are quite difficult to read and comprehend. You can check the screenshots below.

I think it would make things a little easier to understand if we add padding to the table rows, add table outline and alternating rows are styled to become zebra striped. I believe it will even look better. For reference you can check this W3C example.

[nibble0101]

@patricoferris and @avsm. What do you think?

[patricoferris]

That sounds great @nibble0101 is this something you want to work on?

[nibble0101]

@patricoferris No. You seem overwhelmed by the number of applicants #1245 . I am just trying to help. I will work on some issues perhaps later on when the numbers reduce.

[Msgl]

Hi! my name is Maria and I am an Outreachy candidate. Can I work on this issue?

[nibble0101]

@Msgl Sure you can go ahead.

[SowmyaSv]

@avsm @patricoferris @gs0510 I would like to work on this as my good first issue.

[mercybassey]

with this the tables are easy to read and understand. I'd love to work on this issue

[Msgl]

Hello @mercybassey ! Im still working on this issue.

[mercybassey]

And a little responsiveness by adding a vertical scroll bar to the table to help for easier readability @patricoferris

[gs0510]

@mercybassey It's unfair that you went ahead and worked on this issue even though @Msgl said that they were working on this issue. There's a lot of open issues for you to work on, you can work on one of those.

[mercybassey]

I'm so sorry. I actually worked on it because I felt I could work on it as long as it isn't assigned to anyone. Should I close the PR? @gs0510

[gs0510]

@Msgl Are you still working on this issue?

[gs0510]

I'm so sorry. I actually worked on it because I felt I could work on it as long as it isn't assigned to anyone. Should I close the PR? @gs0510

We'll wait for @Msgl , If they are still working we can close your PR. There's a lot of open issues, you can choose from the ones that haven't been assigned.