doc: Use the recommended Scheme format.

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

@@ -1963,13 +1963,14 @@ package looks like this:
 (define-public hello
   (package
     (name "hello")
-    (version "2.8")
+    (version "2.10")
     (source (origin
               (method url-fetch)
               (uri (string-append "mirror://gnu/hello/hello-" version
                                   ".tar.gz"))
               (sha256
-              (base32 "0wqd8sjmxfskrflaxywc7gqw7sfawrfvdxd9skxawzfgyy0pzdz6"))))
+               (base32
+                "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
     (build-system gnu-build-system)
     (arguments `(#:configure-flags '("--enable-silent-rules")))
     (inputs `(("gawk" ,gawk)))

doc/package-hello.scm

@@ -4,13 +4,14 @@
 
 (package
   (name "hello")
-  (version "2.8")
+  (version "2.10")
   (source (origin
             (method url-fetch)
             (uri (string-append "mirror://gnu/hello/hello-" version
                                 ".tar.gz"))
             (sha256
-             (base32 "0wqd8sjmxfskrflaxywc7gqw7sfawrfvdxd9skxawzfgyy0pzdz6"))))
+             (base32
+              "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
   (build-system gnu-build-system)
   (synopsis "Hello, GNU world: An example GNU package")
   (description "Guess what GNU Hello prints!")

gnu/packages/base.scm

@@ -56,7 +56,8 @@ (define-public hello
               (uri (string-append "mirror://gnu/hello/hello-" version
                                   ".tar.gz"))
               (sha256
-             (base32 "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
+               (base32
+                "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
     (build-system gnu-build-system)
     (synopsis "Hello, GNU world: An example GNU package")
     (description