Use squiggly heredoc for gem description example

[bravehager]

Motivation

Using a non-squiggly heredoc adds leading whitespace in the gem description. rubygems.org seems to handle this fine (by relying on HTML ignoring it), but in other contexts it can make it difficult to render the text (e.g. in an editor using an LSP).

I believe the squiggly heredoc is supported on all non-EOL Ruby versions, but I could understand rejecting this change because it might make it impossible to install a gem on EOL versions. Still, felt it was worth opening here.

[deivid-rodriguez]

This should be patched here: https://github.com/rubygems/rubygems/blob/8ffa73df3a250623b13c5bf7ab48ed8b8e84e46f/lib/rubygems/specification.rb#L304, since that's the source of truth for this documentation.

[bravehager]

This should be patched here: https://github.com/rubygems/rubygems/blob/8ffa73df3a250623b13c5bf7ab48ed8b8e84e46f/lib/rubygems/specification.rb#L304, since that's the source of truth for this documentation.

Opened rubygems/rubygems#7373, let me know if I should close this one out.

[deivid-rodriguez]

Thanks! Yes, this one should be closed and the documentation will be automatically updated once the rubygems change is released (next week).