Add HHS75P00120P00168 to funders list for 2.1 docs (#4192)

This updates the sentence under the Funders section discussing NIDILRR
funding to mention the latest contract spanning 2021-2025,
similarly to what is included in 2.2.

---------

Co-authored-by: Kevin White <kevin@w3.org>

acknowledgements/funders.html

@@ -1,4 +1,4 @@
 <section id="enabling-funders">
   <h2>Enabling funders</h2>
-	<p>This publication has been funded in part with U.S. Federal funds from the Health and Human Services, National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR), initially under contract number ED-OSE-10-C-0067 and now under contract number HHSP23301500054C. The content of this publication does not necessarily reflect the views or policies of the U.S. Department of Health and Human Services or the U.S. Department of Education, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.</p>
+	<p>This publication has been funded in part with U.S. Federal funds from the Health and Human Services, National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR), under contract number HHS75P00120P00168 (previously ED-OSE-10-C-0067 and HHSP23301500054C). The content of this publication does not necessarily reflect the views or policies of the U.S. Department of Health and Human Services or the U.S. Department of Education, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.</p>
 </section>