Document that we need Nightly Rust for the full tests

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/docs/build.rst b/docs/build.rst
index 13c1a22c148fbd21e32dccb394d4bacecfa6cb51..1386e80fbe4c71734525c25ef7d4e5ad36404482 100644 (file)
--- a/docs/build.rst
+++ b/docs/build.rst
@@ -57,6 +57,12 @@ Setup
 
    and just dump the resulting ``geckodriver`` binary on your ``PATH``.
 
+5. The tests also use Nightly Rust because we use Miri to test the
+   small amount of ``unsafe`` in the Otter codebase::
+
+     rustup toolchain add nightly
+     rustup +nightly component add miri
+
 
 Full build
 ----------