skia-bindings: update documentation to reflect the new environment variable
@@ -34,6 +34,12 @@ Whenever a new version of `rust-skia` is built from the `release` branch on our
And whenever the build script detects that `skia-bindings` is built from inside a crate _and_ a prebuilt archive is available that matches the repository's hash, platform, and features, it downloads the package, unpacks it, and skips the full build step of Skia and the bindings.
+## Using system libraries
+
+By default numerous libraries Skia depends upon are built in addition to Skia itself. In the event
+that this is not wanted (say, if the crate is being built as part of a package's build routine,)
+this behavior can be disabled by setting the `SKIA_USE_SYSTEM_LIBRARIES` environment variable.
+
## Offline Builds
A full build of Skia downloads several repositories from the Internet. For specific scenarios, like, for example, [a packaging script](https://github.com/rust-skia/rust-skia/issues/340), it can be useful to build Skia offline. To configure that, the build script supports the following environment variables:
