Update 'About Modal' plugin section styling

[epwinchell]

This PR makes the plugin section expandable and also increases the scrollable area to 10 lines.

This is a follow-up to: #4423

[epwinchell]

@miq-bot add_label enhancement, gaprindashvili/no, formatting/styling

[epwinchell]

@miq-bot add_label ux/review

[epwinchell]

@miq-bot assign @terezanovotna

[terezanovotna]

@epwinchell Can we make the scrollable area at least 10 lines? or even more? having to scroll in 4 lines area is not very convenient for the user. If we show 100 items, it is going to be hard to scan all the info while forever scrolling

[miq-bot]

Checked commit https://github.com/epwinchell/manageiq-ui-classic/commit/17ae7998deecdbdf0b3bf47af629ecb6a447cd48 with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
1 file checked, 1 offense detected

**

• 💣 💥 🔥 🚒 - Linter/Haml - Linter::Haml STDERR:

warning: parser/current is loading parser/ruby23, which recognizes
warning: 2.3.6-compliant syntax, but you are running 2.3.3.
warning: please see https://github.com/whitequark/parser#compatibility-with-ruby-mri.

[epwinchell]

@terezanovotna Updated with 10 lines. That's already forcing a scrollbar in the viewport at 1280x800 (unless the browser is at fullscreen.) I wouldn't push it any farther.

[terezanovotna]

@epwinchell that works! You just made it more usable!

@miq-bot remove_label ux/review
@miq-bot add_label ux/approved

[epwinchell]

@miq-bot assign @mzazrivec