SHA256 submodule within SHA1 repo causes problems

Thus, the advice on how to create a git repo is changed.

README.md

@@ -141,7 +141,7 @@ for your ISP and your network interfaces.
 $ cd /etc
 $ mkdir router-conf
 $ cd router-conf
-$ git init .
+$ git init --object-format=sha256 .
 $ git submodule add rc.router https://gitea.nerdland.org/rc.router/rc.router
 $ rc.router/scripts/install-dependencies.sh
 $ cp rc.router/samples/basic/* .
@@ -169,7 +169,7 @@ not IPv4 settings.)
 $ cd /etc
 $ mkdir router-conf
 $ cd router-conf
-$ git init .
+$ git init --object-format=sha256 .
 $ cat << EOF > rc.conf
 # Configure a basic external v4 ISP
 external_card="em0"
@@ -199,7 +199,7 @@ Executing this sequence of sample commands will setup a basic v4 NAT/dhcp router
 $ cd /etc
 $ mkdir router-conf
 $ cd router-conf
-$ git init .
+$ git init --object-format=sha256 .
 $ cat << EOF > rc.conf
 # Configure a basic external v4 ISP
 external_card="em0"