Fix Bugzilla 24488 - contributor guide hard to find from home page

Replace GitHub and Get Involved items under Community menu with
Contributing page.
Add link to bug reporting guidelines.
Contributing: also list dlang-community and github PR guide.

Author: ntrel

book/dlang.org.ddoc

@@ -269,9 +269,8 @@ $(SUBMENU_MANUAL
     $(SUBMENU_LINK irc://irc.libera.chat/d, IRC)
     $(SUBMENU_LINK https://discord.gg/bMZk9Q4, Community Discord)
     $(SUBMENU_LINK https://wiki.dlang.org, Wiki)
-    $(SUBMENU_LINK_DIVIDER https://github.com/dlang, GitHub)
-    $(SUBMENU_LINK $(ROOT_DIR)bugstats.html, Issues)
-    $(SUBMENU_LINK https://wiki.dlang.org/Get_involved, Get involved)
+    $(SUBMENU_LINK_DIVIDER $(ROOT_DIR)bugstats.html, Issues)
+    $(SUBMENU_LINK $(ROOT_DIR)contributing.html, Contributing)
     $(SUBMENU_LINK_DIVIDER $(ROOT_DIR)foundation/contributors.html, Contributors)
     $(SUBMENU_LINK $(ROOT_DIR)foundation/index.html, Foundation)
     $(SUBMENU_LINK $(ROOT_DIR)/security.html, Security Team)

bugstats.dd

@@ -9,15 +9,16 @@ $(P
 )
 
 $(P
-    You can browse through the existing bugs for D projects $(LINK2 https://issues.dlang.org/describecomponents.cgi?product=D, $(B here)).
+    You can browse through the existing bugs by project $(LINK2 https://issues.dlang.org/describecomponents.cgi?product=D, $(B here)).
 )
 
 $(P
     If you want to search for a specific bug, you can use the $(LINK2 https://issues.dlang.org/query.cgi?format=specific, $(B search page)).
 )
 
 $(P
-    And if you want to file a new bug, you can use $(LINK2 https://issues.dlang.org/enter_bug.cgi?product=D, $(B this page)).
+    And if you want to file a new bug, you can use $(LINK2 https://issues.dlang.org/enter_bug.cgi?product=D, $(B this page)),
+    but please $(HTTPS github.com/dlang/dmd/blob/master/CONTRIBUTING.md#reporting-bugs, check the guidelines) first.
 )
 
 $(H3 Bug Tracker Statistics)

contributing.dd

@@ -0,0 +1,22 @@
+Ddoc
+
+$(D_S Contributing,
+
+$(NOTE To search the bug tracker or report issues, see $(LINK2 bugstats.html, Issues).)
+
+$(H2 $(LNAME2 github, GitHub Projects))
+
+* $(LINK2 https://github.com/dlang, dlang) - dmd, phobos, dub, dlang.org etc
+* $(LINK2 https://github.com/dlang-community, dlang-community) - dfmt, dscanner etc
+
+
+$(H2 $(LNAME2 see-also, Getting Started))
+
+* Please read: $(LINK2 https://github.com/dlang/dmd/blob/master/CONTRIBUTING.md#solving-bugs--submitting-pull-requests,
+    Solving bugs / Submitting pull requests)
+* Get involved: $(HTTPS wiki.dlang.org/Get_involved)
+
+)
+
+Macros:
+  TITLE=Contributing

dlang.org.ddoc

@@ -269,9 +269,8 @@ $(SUBMENU_MANUAL
     $(SUBMENU_LINK irc://irc.libera.chat/d, IRC)
     $(SUBMENU_LINK https://discord.gg/bMZk9Q4, Community Discord)
     $(SUBMENU_LINK https://wiki.dlang.org, Wiki)
-    $(SUBMENU_LINK_DIVIDER https://github.com/dlang, GitHub)
-    $(SUBMENU_LINK $(ROOT_DIR)bugstats.html, Issues)
-    $(SUBMENU_LINK https://wiki.dlang.org/Get_involved, Get involved)
+    $(SUBMENU_LINK_DIVIDER $(ROOT_DIR)bugstats.html, Issues)
+    $(SUBMENU_LINK $(ROOT_DIR)contributing.html, Contributing)
     $(SUBMENU_LINK_DIVIDER $(ROOT_DIR)foundation/contributors.html, Contributors)
     $(SUBMENU_LINK $(ROOT_DIR)foundation/index.html, Foundation)
     $(SUBMENU_LINK $(ROOT_DIR)/security.html, Security Team)

posix.mak

@@ -345,7 +345,7 @@ 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) community comparison \
+	ascii-table bugstats $(CHANGELOG_FILES) community comparison contributing \
 	deprecate dmd dmd-freebsd dmd-linux dmd-osx dmd-windows \
 	documentation download dstyle forum-template gpg_keys \
 	howto-promote htod index install \