Update bootstrapping docs to account for new stage meanings

see https://github.com/rust-lang/rust/pull/145253 for reference.
diff --git a/src/building/bootstrapping/what-bootstrapping-does.md b/src/building/bootstrapping/what-bootstrapping-does.md
index da425d8..bfd75eb 100644
--- a/src/building/bootstrapping/what-bootstrapping-does.md
+++ b/src/building/bootstrapping/what-bootstrapping-does.md
@@ -23,7 +23,7 @@
 
 ### Overview
 
-- Stage 0: the pre-compiled compiler
+- Stage 0: the pre-compiled compiler and standard library
 - Stage 1: from current code, by an earlier compiler
 - Stage 2: the truly current compiler
 - Stage 3: the same-result test
@@ -192,7 +192,7 @@
   artifacts'). If you're working on the standard library, this is normally the
   test command you want.
 - `./x build --stage 0` means to build with the stage0 `rustc`.
-- `./x doc --stage 0` means to document using the stage0 `rustdoc`.
+- `./x doc --stage 1` means to document using the stage0 `rustdoc`.
 
 #### Examples of what *not* to do
 
@@ -211,7 +211,7 @@
 In short, _stage 0 uses the `stage0` compiler to create `stage0` artifacts which
 will later be uplifted to be the stage1 compiler_.
 
-In each stage, two major steps are performed:
+In each stage besides 0, two major steps are performed:
 
 1. `std` is compiled by the stage N compiler.
 2. That `std` is linked to programs built by the stage N compiler, including the