doc: fix markdown errors for MD038
doc: fix markdown errors for MD038

MD038 - Spaces inside code span elements
https://github.com/markdownlint/markdownlint/blob/master/docs/RULES.md#md038---spaces-inside-code-span-elements

Signed-off-by: Ruth Fuchss <90c286bb8b7c8291b9f5a2a1d38dc233728381fe@canonical.com>

lxc/lxd,lxc/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,stgraber/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,stgraber/lxd,lxc/lxd,stgraber/lxd,lxc/lxd,lxc/lxd