Tell Prettier to ignore sample plug-in files
Tell Prettier to ignore sample plug-in files

These files are included via coderefs, and require shorter lines to fit in codeblocks.

Amended original commit via `git commit --fixup bc4d67f` (now 76c423f) to remove changes to sample plug-ins.

Signed-off-by: Roger Sheen <a61a1add71dadc74037ae5e44ee30713db9a7451@infotexture.net>

infotexture/docs,infotexture/docs,dita-ot/docs