Updates the landing page (#719)

* Updates the landing page
Changes the order of talks by time

Signed-off-by: Hanan Younes <hanan.algazaley@gmail.com>

* fixes a broken link

Signed-off-by: Hanan Younes <hanan.algazaley@gmail.com>

* fixes the community page link

Signed-off-by: Hanan Younes <hanan.algazaley@gmail.com>

* adds reviewers' feedback

Signed-off-by: Hanan Younes <hanan.algazaley@gmail.com>

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Signed-off-by: Hanan Younes <hanan.algazaley@gmail.com>