v0.6.0

• add extra information to graphviz images output (@fabianlee)
• new --show-created-by option for images to display the command used to
  create image layer (@fabianlee)
• view options (--show-created-by, --incremental, and --no-human) now
  apply to graphviz images output
• updated documentation (@nicksarafa)
• add size to graphviz images output, to support treemaps (@afbjorklund)

$ sha1sum dockviz_*
d52af084de7c8507ce994f5e2139912e3c9832b7  dockviz_darwin_amd64
0a3f9e99189d57c33f999d7f375dc3a0fe596d79  dockviz_linux_amd64
90c06fc4480010df1eaf239e1c7a11e9c62b120c  dockviz_linux_arm
$ sha256sum dockviz_*
1ba3b1e0ee9e79028ac6058fa704f75e03e726e74ac829ec93653157ccef4ffe  dockviz_darwin_amd64
b7cb810d4b45955479a4ea3392f65b0857d7992a9033fde9194dcd425f8dc9ab  dockviz_linux_amd64
18c0eb441b7393ee5263086a17e65429315b5cecff9a019a8041a56b93f60cc4  dockviz_linux_arm
$ md5sum dockviz_*
c09f9abfb1e6b68b3dff444d376481c4  dockviz_darwin_amd64
23c141e4aa00227c3444fd675a6cadd5  dockviz_linux_amd64
af0dfdef33e5410154df7ecc8f94bc67  dockviz_linux_arm