Follow-up the PR #4024 (Greek Language by @psavva)

・Update forgotten Configuration.h of K8400

Marlin/example_configurations/K8400/Configuration.h

@@ -827,10 +827,10 @@ const bool Z_MIN_PROBE_ENDSTOP_INVERTING = true; // set to true to invert the lo
 //
 // Here you may choose the language used by Marlin on the LCD menus, the following
 // list of languages are available:
-//    en, an, bg, ca, cn, cz, de, es, eu, fi, fr, gl, hr, it, kana,
-//    kana_utf8, nl, pl, pt, pt_utf8, pt-br, pt-br_utf8, ru, test
+//    en, an, bg, ca, cn, cz, de, el, el-gr, es, eu, fi, fr, gl, hr, it,
+//    kana, kana_utf8, nl, pl, pt, pt_utf8, pt-br, pt-br_utf8, ru, test
 //
-// :{'en':'English','an':'Aragonese','bg':'Bulgarian','ca':'Catalan','cn':'Chinese','cz':'Czech','de':'German','es':'Spanish','eu':'Basque-Euskera','fi':'Finnish','fr':'French','gl':'Galician','hr':'Croatian','it':'Italian','kana':'Japanese','kana_utf8':'Japanese (UTF8)','nl':'Dutch','pl':'Polish','pt':'Portuguese','pt-br':'Portuguese (Brazilian)','pt-br_utf8':'Portuguese (Brazilian UTF8)','pt_utf8':'Portuguese (UTF8)','ru':'Russian','test':'TEST'}
+// :{'en':'English','an':'Aragonese','bg':'Bulgarian','ca':'Catalan','cn':'Chinese','cz':'Czech','de':'German','el':'Greek','el-gr':'Greek (Greece)','es':'Spanish','eu':'Basque-Euskera','fi':'Finnish','fr':'French','gl':'Galician','hr':'Croatian','it':'Italian','kana':'Japanese','kana_utf8':'Japanese (UTF8)','nl':'Dutch','pl':'Polish','pt':'Portuguese','pt-br':'Portuguese (Brazilian)','pt-br_utf8':'Portuguese (Brazilian UTF8)','pt_utf8':'Portuguese (UTF8)','ru':'Russian','test':'TEST'}
 //
 #define LCD_LANGUAGE en
 

Marlin/example_configurations/K8400/Dual Heads/Configuration.h

@@ -827,10 +827,10 @@ const bool Z_MIN_PROBE_ENDSTOP_INVERTING = true; // set to true to invert the lo
 //
 // Here you may choose the language used by Marlin on the LCD menus, the following
 // list of languages are available:
-//    en, an, bg, ca, cn, cz, de, es, eu, fi, fr, gl, hr, it, kana,
-//    kana_utf8, nl, pl, pt, pt_utf8, pt-br, pt-br_utf8, ru, test
+//    en, an, bg, ca, cn, cz, de, el, el-gr, es, eu, fi, fr, gl, hr, it,
+//    kana, kana_utf8, nl, pl, pt, pt_utf8, pt-br, pt-br_utf8, ru, test
 //
-// :{'en':'English','an':'Aragonese','bg':'Bulgarian','ca':'Catalan','cn':'Chinese','cz':'Czech','de':'German','es':'Spanish','eu':'Basque-Euskera','fi':'Finnish','fr':'French','gl':'Galician','hr':'Croatian','it':'Italian','kana':'Japanese','kana_utf8':'Japanese (UTF8)','nl':'Dutch','pl':'Polish','pt':'Portuguese','pt-br':'Portuguese (Brazilian)','pt-br_utf8':'Portuguese (Brazilian UTF8)','pt_utf8':'Portuguese (UTF8)','ru':'Russian','test':'TEST'}
+// :{'en':'English','an':'Aragonese','bg':'Bulgarian','ca':'Catalan','cn':'Chinese','cz':'Czech','de':'German','el':'Greek','el-gr':'Greek (Greece)','es':'Spanish','eu':'Basque-Euskera','fi':'Finnish','fr':'French','gl':'Galician','hr':'Croatian','it':'Italian','kana':'Japanese','kana_utf8':'Japanese (UTF8)','nl':'Dutch','pl':'Polish','pt':'Portuguese','pt-br':'Portuguese (Brazilian)','pt-br_utf8':'Portuguese (Brazilian UTF8)','pt_utf8':'Portuguese (UTF8)','ru':'Russian','test':'TEST'}
 //
 #define LCD_LANGUAGE en