docs: Document how to ship pre-built tools (#117)

Fixes #57

Author: alexeagle

README.md

@@ -4,7 +4,7 @@ Copy this template to create a Bazel ruleset.
 
 Features:
 
-- follows the official style guide at https://docs.bazel.build/versions/main/skylark/deploying.html
+- follows the official style guide at https://bazel.build/rules/deploying
 - allows for both WORKSPACE.bazel and bzlmod (MODULE.bazel) usage
 - includes Bazel formatting as a pre-commit hook (using [buildifier])
 - includes stardoc API documentation generator
@@ -13,10 +13,6 @@ Features:
 - release using GitHub Actions just by pushing a tag
 - the release artifact doesn't need to be built by Bazel, but can still exclude files and stamp the version
 
-See https://docs.bazel.build/versions/main/skylark/deploying.html#readme
-
-[buildifier]: https://github.com/bazelbuild/buildtools/tree/master/buildifier#readme
-
 Ready to get started? Copy this repo, then
 
 1. search for "com_myorg_rules_mylang" and replace with the name you'll use for your workspace
@@ -28,6 +24,12 @@ Ready to get started? Copy this repo, then
 1. (optional) install the [Renovate app](https://github.com/apps/renovate) to get auto-PRs to keep the dependencies up-to-date.
 1. delete this section of the README (everything up to the SNIP).
 
+Optional: if you write tools for your rules to call, you should avoid toolchain dependencies for those tools leaking to all users.
+For example, https://github.com/aspect-build/rules_py actions rely on a couple of binaries written in Rust, but we don't want users to be forced to
+fetch a working Rust toolchain. Instead we want to ship pre-built binaries on our GH releases, and the ruleset fetches these as toolchains.
+See https://blog.aspect.build/releasing-bazel-rulesets-rust for information on how to do this.
+Note that users who *do* want to build tools from source should still be able to do so, they just need to register a different toolchain earlier.
+
 ---- SNIP ----
 
 # Bazel rules for mylang