scripts: gitlint: Fix broken module docstring

Needs to be at the beginning of the file. Fixes a pylint warning:

    scripts/process_gperf.py:26:-1: W0105: String statement has no
    effect (pointless-string-statement)

Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>

scripts/gitlint/zephyr_commit_rules.py

@@ -1,7 +1,3 @@
-from gitlint.rules import CommitRule, RuleViolation, TitleRegexMatches, CommitMessageTitle, LineRule, CommitMessageBody
-from gitlint.options import IntOption, BoolOption, StrOption, ListOption
-import re
-
 """
 The classes below are examples of user-defined CommitRules. Commit rules are gitlint rules that
 act on the entire commit at once. Once the rules are discovered, gitlint will automatically take care of applying them
@@ -15,6 +11,10 @@ While every LineRule can be implemented as a CommitRule, it's usually easier and
 that fits your needs.
 """
 
+from gitlint.rules import CommitRule, RuleViolation, TitleRegexMatches, CommitMessageTitle, LineRule, CommitMessageBody
+from gitlint.options import IntOption, BoolOption, StrOption, ListOption
+import re
+
 class BodyMinLineCount(CommitRule):
     # A rule MUST have a human friendly name
     name = "body-min-line-count"