[docs] Update, improve/refresh, and fix <rh-card> docs

[markcaron]

Description

<rh-card> docs are out of date and need lots of updating.

Here are a few things that need updates/fixes:

1. Card's Style Theme screenshots show inconsistent "Title" bar styles that don't follow DPO guidelines. The light theme's isn't sentence case and the dark theme's still has ALL CAPS (see screenshots below).
2. Card's Style Theme Color screenshots appear to be missing/broken (see screenshot below)
3. Card's Style Theme Layout screenshot still shows ALL CAPS in the "Title" bar (see screenshot below)
4. Card's Demos seem to have some issues, particularly the "Title" bar pattern which is still ALL CAPS

Please add more items above as you see more issues.

Links

No response

Screenshots

1) Style Themes

2) Style Theme Color

3) Style Theme Layout