fix(docker): Package bootstrap script so Docker images can be built from source tarballs

Author: alerque

Makefile.am

@@ -72,7 +72,7 @@ dist_pdf_DATA = $(_MANUAL)
 dist_license_DATA = LICENSE.md
 EXTRA_DIST = spec tests documentation sile-dev-1.rockspec rusile-dev-1.rockspec fontconfig.conf
 EXTRA_DIST += build-aux/action-updater.js build-aux/cargo-updater.js build-aux/config.ld build-aux/decore-automake.sh build-aux/git-version-gen
-EXTRA_DIST += Dockerfile build-aux/docker-bootstrap.sh build-aux/docker-fontconfig.conf hooks/build
+EXTRA_DIST += Dockerfile bootstrap.sh build-aux/docker-bootstrap.sh build-aux/docker-fontconfig.conf hooks/build
 EXTRA_DIST += build-aux/xml-entities-to-lua.xsl
 EXTRA_DIST += default.nix flake.nix flake.lock shell.nix build-aux/pkg.nix
 EXTRA_DIST += package.json # imported by both Nix and Docker