README.Cygwin: if using git, make sure to checkout with Unix line endings.

bootstrap/README.Cygwin

@@ -1,9 +1,23 @@
-$NetBSD: README.Cygwin,v 1.2 2016/07/03 15:16:47 sevan Exp $
+$NetBSD: README.Cygwin,v 1.3 2022/12/06 15:22:18 schmonz Exp $
 
 Please read the general README file as well.
 
 ==========================================================================
 
+If fetching pkgsrc via git, make sure you get it with Unix line endings:
+
+	$ git clone https://github.com/NetBSD/pkgsrc.git \
+	    --config core.eol=lf \
+	    --config core.autocrlf=input
+
+If you've already fetched pkgsrc without these options, fix up the line
+endings now:
+
+	$ cd pkgsrc
+	$ git config core.eol lf
+	$ git config core.autocrlf input
+	$ git checkout-index --force --all
+
 pkgsrc supports both gcc (GNU Compiler Collection) and clang (C Language Family
 Frontend for LLVM). gcc is the default.