docs: kernel-doc: properly recognize parameter lines with colons

The previous attempt to properly handle literal blocks broke parsing of
parameter lines containing colons; fix it by tweaking the regex to
specifically exclude the "::" pattern while accepting lines containing
colons in general.  Add a little documentation to the regex while in the
neighborhood.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 8d295fba ("kernel-doc: better handle '::' sequences")
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

scripts/kernel-doc

@@ -391,8 +391,14 @@ my $doc_com = '\s*\*\s*';
 my $doc_com_body = '\s*\* ?';
 my $doc_decl = $doc_com . '(\w+)';
 # @params and a strictly limited set of supported section names
+# Specifically:
+#   Match @word:
+#	  @...:
+#         @{section-name}:
+# while trying to not match literal block starts like "example::"
+#
 my $doc_sect = $doc_com .
-    '\s*(\@[.\w]+|\@\.\.\.|description|context|returns?|notes?|examples?)\s*:([^:]*)$';
+    '\s*(\@[.\w]+|\@\.\.\.|description|context|returns?|notes?|examples?)\s*:([^:].*)?$';
 my $doc_content = $doc_com_body . '(.*)';
 my $doc_block = $doc_com . 'DOC:\s*(.*)?';
 my $doc_inline_start = '^\s*/\*\*\s*$';