Fix section titles with emojis

[jdidion]

Since WDL 1.1 we've been using emojis to mark new and deprecated features. However, the links for these sections are broken in the ToC in some editors (e.g. VS Code). It is unclear whether this behavior is inherent or caused by a plugin.

Note that the ToC links still work fine in GitHub, so this should be considered a minor issue. If there is no good fix that works with GitHub then things should be left as-is and this issue reported to the IDE/plugin developers.