Update docs to use new template locator

[unsuman]

Since Lima v2.0, Examples/Containers/* of the docs still contains the outdated template://* which should be updated to template:*.

[Alisha-Rehman]

Hi! I’d like to work on this issue. Could you please assign it to me?

[AkihiroSuda]

Until we can be sure that people have switched to v2 (which will be after the EOL of v1 in the next February) we have to retain the v1 form as well

e.g.,

# NOTE: Lima v1 users have to use `template://foo`, not `template:foo`
limactl start template:foo

[jandubois]

This was all part of #4286, but @AkihiroSuda made me remove it again.

Note that the actual "work" to change it is trivial (as long as you don't have to add the v1 comment):

find . -type f -name '*.md' -exec perl -p -i -e 's|template://|template:|' {} \;

You don't want to modify the code; there are unit tests that intentionally reference the old format to make sure it is still supported.