Docs/damon/maintainer-profile: document Google calendar for bi-weekly meetups

We added a public Google calendar for easy sharing of DAMON bi-weekly
meetups[1].  Add it to the official document for a better visibility.

[1] https://lore.kernel.org/all/20240717235812.53087-1-sj@kernel.org/

Link: https://lkml.kernel.org/r/20240826015741.80707-4-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Alex Shi <alexs@kernel.org>
Cc: Hu Haowen <2023002089@link.tyut.edu.cn>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>