docs: document need for rustfmt, have ./check look for it

Sponsored-by: author

1 files changed, 1 insertions, 0 deletions

diff --git a/check b/check
index 2920d24..533ac50 100755
--- a/check
+++ b/check
@@ -343,6 +343,7 @@ def check_tooling(r):
         "pdflatex",
         "plantuml",
         "rustc",
+        "rustfmt",
     ]
     for command in commands:
         if not r.got_command(command):