Site: Remove vote email from release instructions, and minor improvements
Site: Remove vote email from release instructions, and minor improvements

A draft email with the same content is printed by Gradle `prepareVote`
task so we can remove it from the site to avoid maintaining both
versions.

julianhyde/calcite,apache/calcite,apache/calcite,julianhyde/calcite,apache/calcite,apache/calcite,looker-open-source/calcite,looker-open-source/calcite,julianhyde/calcite,julianhyde/calcite,looker-open-source/calcite,looker-open-source/calcite,looker-open-source/calcite,apache/calcite,julianhyde/calcite,julianhyde/calcite,apache/calcite,looker-open-source/calcite