Add possible Schematron documentation checks

This is the product of the meeting and spike where we pair-programmed
and came up with example Schematron rules for tentative editorial
standards that can be used for reviews of models and embedded docs as
part of #801.

Co-authored-by: Chris Compton <[email protected]>
Co-authored-by: Rene Rene Tshiteya <[email protected]>
Co-authored-by: Wendell Piez <[email protected]>

src/utils/schematron/oscal-documentation.sch

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<sch:schema xmlns:sch="http://purl.oclc.org/dsdl/schematron" queryBinding="xslt2"
+    xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+    xmlns:m="http://csrc.nist.gov/ns/oscal/metaschema/1.0"
+    xmlns:nm="http://csrc.nist.gov/ns/metaschema"
+    xmlns:sqf="http://www.schematron-quickfix.com/validator/process"
+    xmlns:oscal="http://csrc.nist.gov/ns/oscal/1.0">
+
+    <sch:ns uri="http://csrc.nist.gov/ns/oscal/metaschema/1.0" prefix="m"/>
+    <sch:ns uri="http://csrc.nist.gov/ns/metaschema" prefix="nm"/>
+
+    <sch:pattern>
+        <sch:rule context="m:description">
+            <sch:assert role="error" test="ends-with(.,'.')" id="description-ends-with-dot">Description should end with a period.</sch:assert>
+            <sch:assert role="error" test="string-length(.) gt 6" id="description-long-enough">Description is too short.</sch:assert>
+        </sch:rule>
+    </sch:pattern>
+</sch:schema>