🚀 Feature: Increasing SVG icon libraries count

### Description

I see that this repository adds only one icon library, aside of SimpleIcons used by shields.io, which is a shame.

**Is there a possibility of adding more icon libraries?** I understand that this increase bandwidth or cause other issues, nonetheless I dare to say that amounts of icons in the Octicons library may be insufficient for some cases, since there are only around 250 of them, which - compared to library used by shields - *feels* like a small fraction.

Here is a table (sorted by stars amount) containing worth-checking repositories with icons:
| Supported | Repository | Author | Icons¹ | Stars | Primary Language | License |
|:-:|:-:|:-:|:-:|:-:|:-:|:-:|
| #959 | [feather](https://github.com/feathericons/feather) | [feathericons](https://github.com/feathericons) | 1953 | 23787 | `84.3%` JavaScript | MIT |
| | [ionicons](https://github.com/ionic-team/ionicons) | [ionic-team](https://github.com/ionic-team) | 1338 | 17032 | `76.7%` TypeScript | MIT |
| | [tabler-icons](https://github.com/tabler/tabler-icons) | [tabler](https://github.com/tabler) | 4619 | 15862 | `56.3%` HTML | MIT |
| | [flag-icons](https://github.com/lipis/flag-icons) | [lipis](https://github.com/lipis) | 268 | 9657 | `59.8%` CSS | MIT |
| | [icons](https://github.com/twbs/icons) | [twbs](https://github.com/twbs) | 287 | 6856 | `96.4%` JavaScript | MIT |
| | [weather-icons](https://github.com/erikflowers/weather-icons) | [erikflowers](https://github.com/erikflowers) | 222 | 6721 | `59.7%` CSS | SIL OFL 1.1 |

¹ - esmaited amount, counted from repository files

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If introduced - what I'm looking straightforward to - libraries in URLs can be distinguished by their names.
- `logo=paintbrush` -> `logo=octicons-paintbrush`