Revert "embed dlang calendar on dlang.org/calendar"

Author: ibuclaw

calendar.dd

@@ -264,7 +264,6 @@ $(SUBMENU_MANUAL
     $(SUBMENU_LINK https://dlang.org/blog, Blog)
     $(SUBMENU_LINK $(ROOT_DIR)orgs-using-d.html, Orgs using D)
     $(SUBMENU_LINK https://twitter.com/search?q=%23dlang, Twitter)
-    $(SUBMENU_LINK $(ROOT_DIR)calendar.html, Calendar)
     $(SUBMENU_LINK_DIVIDER https://forum.dlang.org, Forums)
     $(SUBMENU_LINK irc://irc.libera.chat/d, IRC)
     $(SUBMENU_LINK https://discord.gg/bMZk9Q4, Community Discord)

dlang.org.ddoc

@@ -344,7 +344,7 @@ ARTICLE_FILES=$(addprefix articles/, index builtin code_coverage const-faq \
 # and .html in the generated HTML. Save for the expansion of
 # $(SPEC_ROOT), the list is sorted alphabetically.
 PAGES_ROOT=$(SPEC_ROOT) 404 acknowledgements areas-of-d-usage $(ARTICLE_FILES) \
-	ascii-table bugstats $(CHANGELOG_FILES) calendar community comparison concepts \
+	ascii-table bugstats $(CHANGELOG_FILES) community comparison concepts \
 	deprecate dmd dmd-freebsd dmd-linux dmd-osx dmd-windows \
 	documentation download dstyle forum-template gpg_keys glossary \
 	howto-promote htod index install \