* modified overview page * updated text and image * fixed spelling errors * Update website/content/docs/what-is-boundary.mdx Co-authored-by: Yoko Hyakuna <yoko@hashicorp.com> * Update website/content/docs/what-is-boundary.mdx Co-authored-by: Robin Beck <stellarsquall@users.noreply.github.com> * Update website/content/docs/what-is-boundary.mdx Co-authored-by: Robin Beck <stellarsquall@users.noreply.github.com> * Update website/content/docs/what-is-boundary.mdx Co-authored-by: Robin Beck <stellarsquall@users.noreply.github.com> * Update website/content/docs/what-is-boundary.mdx Co-authored-by: Robin Beck <stellarsquall@users.noreply.github.com> * Update website/content/docs/what-is-boundary.mdx Co-authored-by: Robin Beck <stellarsquall@users.noreply.github.com> * cleaned up content * Update website/content/docs/what-is-boundary.mdx Co-authored-by: XingLu Wang <95828202+xingluw@users.noreply.github.com> * incorporate feedback * updated image * updated background color * modified font * Update website/content/docs/what-is-boundary.mdx Co-authored-by: Yoko Hyakuna <yoko@hashicorp.com> Co-authored-by: Yoko Hyakuna <yoko@hashicorp.com> Co-authored-by: Robin Beck <stellarsquall@users.noreply.github.com> Co-authored-by: XingLu Wang <95828202+xingluw@users.noreply.github.com>