Fixes broken server doc link to bottomless replication

[a-poor]

Fixes the broken link to the bottomless replication subproject in the libsql-server documentation.

Original link pointed to https://github.com/tursodatabase/libsql/blob/main/libsql-server/bottomless

Link should point to: https://github.com/tursodatabase/libsql/blob/main/bottomless

[avinassh]

Thank you!