doc: Add documentation-generating scripts to the Crashpad tree

doc/asciidoc.conf

+# Copyright 2015 The Crashpad Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+[miscellaneous]
+# AsciiDoc uses \r\n by default.
+newline=\n
+
+# The default AsciiDoc lang-en.conf uses docdate and doctime for the
+# last-updated line in footer-text. These attributes are taken from the file’s
+# mtime and cannot be overridden. For a git-based project, the date of the last
+# revision is desirable, so change this to use revdate, an attribute that can be
+# computed and passed in by the script that runs AsciiDoc. For man pages, use
+# the mansource and manversion attributes instead of the hard-coded “Version”
+# string and revnumber attribute, so that the version will appear as “Crashpad
+# 0.7.0” as it does in “man” output.
+ifdef::basebackend-html[]
+[footer-text]
+{mansource=Version} {manversion={revnumber}}{basebackend-xhtml11?<br />}{basebackend-xhtml11=<br>}
+Last updated {revdate}
+endif::basebackend-html[]