Super Rudimentary DOCX -> Markdown XSL Template - not full featured, and very MSWord specific

docx_to_markdown.xslt

<?xml version="1.0"?>

<xsl:stylesheet
    version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main"
>
    <xsl:output method="text"/>

    <xsl:template match="//w:p">
        <!-- Paragraph level tweaks (prefixes) -->
        <xsl:choose>
            <xsl:when test="./w:pPr/w:pStyle[@w:val='Heading1']">
                <xsl:text># </xsl:text>
            </xsl:when>
            <xsl:when test="./w:pPr/w:pStyle[@w:val='Heading2']">
                <xsl:text>## </xsl:text>
            </xsl:when>
            <xsl:when test="./w:pPr/w:pStyle[@w:val='Heading3']">
                <xsl:text>### </xsl:text>
            </xsl:when>
            <xsl:when test="./w:pPr/w:pStyle[@w:val='Heading4']">
                <xsl:text>#### </xsl:text>
            </xsl:when>
            <xsl:when test="./w:pPr/w:pStyle[@w:val='Heading5']">
                <xsl:text>##### </xsl:text>
            </xsl:when>
            <!-- Unordered list -->
            <!-- WARNING: we can't tell the difference between ordered -->
            <!-- and unordered without looking at additional XML content -->
            <!-- from the docx.  Don't do ordered lists. -->
            <xsl:when test="./w:pPr/w:pStyle[@w:val='Compact']">
                <xsl:text>* </xsl:text>
            </xsl:when>
        </xsl:choose>

        <!-- Content extraction and formatting for the current block -->
        <xsl:for-each select="./w:r">

            <!-- If it's preformatted, use those.  Otherwise, stack up the  -->
            <!-- bold/italic indicators.  Markdown is very nice in that the -->
            <!-- start and end formatters are exactly the same.             -->
            <xsl:variable name="fmt">
                <xsl:choose>
                    <xsl:when test="./w:rPr/w:rStyle[@w:val='VerbatimChar']">
                        <xsl:text>```</xsl:text>
                    </xsl:when>
                    <xsl:otherwise>
                        <xsl:if test="./w:rPr/w:i">
                            <xsl:text>*</xsl:text>
                        </xsl:if>
                        <xsl:if test="./w:rPr/w:b">
                            <xsl:text>**</xsl:text>
                        </xsl:if>
                    </xsl:otherwise>
                </xsl:choose>
            </xsl:variable>

            <!-- Format on the way in... -->
            <xsl:value-of select="$fmt"/>
            <!-- actual value -->
            <xsl:value-of select="./w:t"/>
            <!-- ...format on the way out. -->
            <xsl:value-of select="$fmt"/>

        </xsl:for-each>

        <!-- Paragraph Separator (double carriage return) -->
        <xsl:choose>
            <!-- If we are a list, and the next entry is ALSO part of a -->
            <!-- list, only do a single carriage retrurn. -->
            <xsl:when test="(
                ./w:pPr/w:pStyle[@w:val='Compact']
            ) and (
                ./following-sibling::*[1]/w:pPr/w:pStyle[@w:val='Compact']
            )">
                <!-- single carriage return in lists -->
                <xsl:text>&#10;</xsl:text>
            </xsl:when>
            <xsl:otherwise>
                <!-- Multiple carriage returns to separate blocks. -->
                <xsl:text>&#10;&#10;</xsl:text>
            </xsl:otherwise>
        </xsl:choose>
    </xsl:template>

</xsl:stylesheet>

Useful for something like:

unzip -c my_file.docx "word/document.xml" | tail -n +3 | xsltproc word_to_markdown.xslt -