feat: add OpenGraph and Twitter attributes to header

[IdanCo]

This update includes OpenGraph and Twitter attributes in the HTML header. This enhances sharing experiences on social media. Shared content now presents more rich and relevant information.

PR Checklist

Please check if your PR fulfills the following requirements:

• [x] The commit message follows our guidelines: https://github.com/ngneat/elf/blob/master/CONTRIBUTING.md#commit
• [ ] Tests for the changes have been added (for bug fixes / features)
• [x] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[x] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

As can be seen here, sharing Elf's url does not look good -

What is the new behavior?

When this changes are deployed, sharing Elf would look like this -

Does this PR introduce a breaking change?

[ ] Yes
[ X] No

Other information

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