hooks: set up sparse checkout after cloning the vcsh repository

Make sure to correctly configure sparse checkout right after the vcsh
repository has been cloned with 'vcsh clone'.

This is needed to avoid leaving conflicting files (e.g. README) in the
working tree, which would prevent other vcsh repositories from being
cloned without errors.

diff --git a/.config/vcsh/hooks-enabled/vcsh.post-clone.00-enable-sparse-checkout.sh b/.config/vcsh/hooks-enabled/vcsh.post-clone.00-enable-sparse-checkout.sh
new file mode 120000 (symlink)
index 0000000..689d439
--- /dev/null
+++ b/.config/vcsh/hooks-enabled/vcsh.post-clone.00-enable-sparse-checkout.sh
@@ -0,0 +1 @@
+../hooks-available/enable-sparse-checkout.sh
\ No newline at end of file

diff --git a/.config/vcsh/hooks-enabled/vcsh.post-clone.01-update-working-tree.sh b/.config/vcsh/hooks-enabled/vcsh.post-clone.01-update-working-tree.sh
new file mode 120000 (symlink)
index 0000000..cdf7637
--- /dev/null
+++ b/.config/vcsh/hooks-enabled/vcsh.post-clone.01-update-working-tree.sh
@@ -0,0 +1 @@
+../hooks-available/update-working-tree.sh
\ No newline at end of file