Because not all Void kernels may support zstd, change the default initramfs
compression to gzip.

diff -ur a/man/mkinitcpio.conf.5.adoc b/man/mkinitcpio.conf.5.adoc
--- a/man/mkinitcpio.conf.5.adoc
+++ b/man/mkinitcpio.conf.5.adoc
@@ -55,7 +55,7 @@
     Defines a program to filter the generated image through. The kernel
     understands the compression formats yielded by the *zstd*(1), *gzip*(1),
     *bzip2*(1), *lz4*(1), *lzop*(1), *lzma*(1), and *xz*(1) compressors. If
-    unspecified, this setting defaults to _zstd_ compression. In order to create
+    unspecified, this setting defaults to _gzip_ compression. In order to create
     an uncompressed image, define this variable as _cat_.
      +
     It is not hard to realize that a filter such as a _tac_ or _rev_ will cause
diff -ur a/mkinitcpio b/mkinitcpio
--- a/mkinitcpio
+++ b/mkinitcpio
@@ -998,7 +998,7 @@
         die "Unable to write to '%s'" "$_optgenimg"
     fi
 
-    _optcompress="${_optcompress:-"${COMPRESSION:-zstd}"}"
+    _optcompress="${_optcompress:-"${COMPRESSION:-gzip}"}"
     if ! type -P "$_optcompress" >/dev/null; then
         warning "Unable to locate compression method: '%s'" "$_optcompress"
         _optcompress='cat'
diff -ur a/mkinitcpio.conf b/mkinitcpio.conf
--- a/mkinitcpio.conf
+++ b/mkinitcpio.conf
@@ -55,7 +55,7 @@
 HOOKS=(base udev autodetect microcode modconf kms keyboard keymap consolefont block filesystems fsck)
 
 # COMPRESSION
-# Use this to compress the initramfs image. By default, zstd compression
+# Use this to compress the initramfs image. By default, gzip compression
 # is used. Use 'cat' to create an uncompressed image.
 #COMPRESSION="zstd"
 #COMPRESSION="gzip"
