docs(pipstar): add more docs to make it ready for release (#3323)

Followup to #3225 to add more documentation.

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index cc59e38..002a57d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -81,7 +81,8 @@
   With this release we are deprecating {obj}`pip.parse.experimental_target_platforms` and
   {obj}`pip_repository.experimental_target_platforms`. For users using `WORKSPACE` and
   vendoring the `requirements.bzl` file, please re-vendor so that downstream is unaffected
-  when the APIs get removed.
+  when the APIs get removed. If you need to customize the way the dependencies get
+  evaluated, see [our docs](/pypi/download.html#customizing-requires-dist-resolution) on customizing `Requires-Dist` resolution.
 
 {#v0-0-0-fixed}
 ### Fixed

docs/environment-variables.md

diff --git a/docs/environment-variables.md b/docs/environment-variables.md
index 4913e32..f0cf777 100644
--- a/docs/environment-variables.md
+++ b/docs/environment-variables.md
@@ -71,6 +71,9 @@
 
 :::{versionadded} 1.5.0
 :::
+:::{versionchanged} VERSION_NEXT_FEATURE
+Flipped to be enabled by default.
+:::
 ::::
 
 ::::{envvar} RULES_PYTHON_EXTRACT_ROOT

docs/pypi/download.md

diff --git a/docs/pypi/download.md b/docs/pypi/download.md
index 7f4e205..c40f2d4 100644
--- a/docs/pypi/download.md
+++ b/docs/pypi/download.md
@@ -168,11 +168,6 @@
 
 ### Customizing `Requires-Dist` resolution
 
-:::{note}
-Currently this is disabled by default, but you can turn it on using 
-{envvar}`RULES_PYTHON_ENABLE_PIPSTAR` environment variable.
-:::
-
 In order to understand what dependencies to pull for a particular package,
 `rules_python` parses the `whl` file [`METADATA`][metadata].
 Packages can express dependencies via `Requires-Dist`, and they can add conditions using