Apply the recommended formatting rules from '.dir-locals.el' to the
examples in the manual in order to fulfill it's purpose of being a
reference.

* doc/package-hello.scm: Indent it.
* doc/guix.texi (Defining Packages, Version Numbers): Likewise.
* gnu/packages/base.scm (hello): Be consistent with the manual.
---
 doc/guix.texi         | 31 ++++++++++++++++---------------
 doc/package-hello.scm |  5 +++--
 gnu/packages/base.scm | 29 +++++++++++++++--------------
 3 files changed, 34 insertions(+), 31 deletions(-)