fix: add missing keyword to suggestions (#2653)

Author: KutluOzel-b

server/engine/src/main/resources/LanguageKeywords.txt

@@ -2408,6 +2408,7 @@ YES=
 YYDDD=
 YYDDMM=
 YW=
+YYMMDD=
 YYYYDDD=The conceptual data items DATE, DATE YYYYMMDD, DAY, DAY YYYYDDD, DAY-OF-WEEK, and TIME implicitly have USAGE DISPLAY. Because these are conceptual data items, they cannot be described in the COBOL program.<br>[Read more](https://www.ibm.com/support/knowledgecenter/en/SS6SG3_6.2.0/com.ibm.cobol62.ent.doc/PGandLR/ref/rlpsaccec.html)<br>\u00A9 Copyright IBM Corporation 1994, 2019.<br>U.S. Government Users Restricted Rights - Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
 YYYYDDMM=
 YYYYMMDD=The conceptual data items DATE, DATE YYYYMMDD, DAY, DAY YYYYDDD, DAY-OF-WEEK, and TIME implicitly have USAGE DISPLAY. Because these are conceptual data items, they cannot be described in the COBOL program.<br>[Read more](https://www.ibm.com/support/knowledgecenter/en/SS6SG3_6.2.0/com.ibm.cobol62.ent.doc/PGandLR/ref/rlpsaccec.html)<br>\u00A9 Copyright IBM Corporation 1994, 2019.<br>U.S. Government Users Restricted Rights - Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp.