Don't try to linkcheck nist links for the time being (#4668)

diff --git a/docs/conf.py b/docs/conf.py
index 2264aff..39fa4f1 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -181,4 +181,6 @@
 linkcheck_ignore = [
     # Small DH key results in a TLS failure on modern OpenSSL
     "https://info.isl.ntt.co.jp/crypt/eng/camellia/",
+    # Federal government shutdown, and the anti-deficiency act
+    r"^https://[\w\.]+?\.nist\.gov/.*",
 ]