I find that Hugo should contain more links to relevant documentation of features in other tools/documentations. Please let me know if we don't want that and I'll stop. In this specific case I read about `.mailmap` in the Hugo docs and as a developer knew what was meant, but I think less dev-y users might not understand this. Instead of starting to add paragraphs about the format maybe it's ok to link to the features docs? As I said, let me know if that is overkill/bloat. It would make my life easier than seeing a word and googling it :)
(for instance, if we link to git in this case we don't need to add extra-documentation about what the mailmap file should look like and what should be in there)
This ommmit contains some security hardening measures for the Hugo build runtime.
There are some rarely used features in Hugo that would be good to have disabled by default. One example would be the "external helpers".
For `asciidoctor` and some others we use Go's `os/exec` package to start a new process.
These are a predefined set of binary names, all loaded from `PATH` and with a predefined set of arguments. Still, if you don't use `asciidoctor` in your project, you might as well have it turned off.
You can configure your own in the new `security` configuration section, but the defaults are configured to create a minimal amount of site breakage. And if that do happen, you will get clear instructions in the loa about what to do.
The default configuration is listed below. Note that almost all of these options are regular expression _whitelists_ (a string or a slice); the value `none` will block all.
```toml
[security]
enableInlineShortcodes = false
[security.exec]
allow = ['^dart-sass-embedded$', '^go$', '^npx$', '^postcss$']
osEnv = ['(?i)^(PATH|PATHEXT|APPDATA|TMP|TEMP|TERM)$']
[security.funcs]
getenv = ['^HUGO_']
[security.http]
methods = ['(?i)GET|POST']
urls = ['.*']
```
