Merge bitcoin#26313: doc: consolidate library documentation to libraries.md

af781bf doc: fix typo in doc/libraries.md (fanquake)
9e9ae61 doc: remove library commentary from src/Makefile.am (fanquake)

Pull request description:

  Deduplicate the makefile comments, in favour of doc/libraries.md. I think a single, more comprehensive source of truth is preferable. Diagrams are also useful. Came up in bitcoin#26292 (comment).

ACKs for top commit:
  ryanofsky:
    Code review ACK af781bf, nice cleanups
  hebasto:
    ACK af781bf, I have reviewed the code and it looks OK, I agree it can be merged.

Tree-SHA512: df61ed1394102221701ae2dfa42886dfabe9d9fd7f601b794e2195f93d8f7c2a1cd1c000a77d0a969b42328e8ebc0387755c57291837b283fdf376dbd98fdda1

Author: MacroFake

doc/design/libraries.md

@@ -83,7 +83,7 @@ class bitcoin-qt,bitcoind,bitcoin-cli,bitcoin-wallet bold
 
 </td></tr></table>
 
-- The graph shows what _linker symbols_ (functions and variables) from each library other libraries can call and reference directly, but it is not a call graph. For example, there is no arrow connecting *libbitcoin_wallet* and *libbitcoin_node* libraries, because these libraries are intended to be modular and not depend on each other's internal implementation details. But wallet code still is still able to call node code indirectly through the `interfaces::Chain` abstract class in [`interfaces/chain.h`](../../src/interfaces/chain.h) and node code calls wallet code through the `interfaces::ChainClient` and `interfaces::Chain::Notifications` abstract classes in the same file. In general, defining abstract classes in [`src/interfaces/`](../../src/interfaces/) can be a convenient way of avoiding unwanted direct dependencies or circular dependencies between libraries.
+- The graph shows what _linker symbols_ (functions and variables) from each library other libraries can call and reference directly, but it is not a call graph. For example, there is no arrow connecting *libbitcoin_wallet* and *libbitcoin_node* libraries, because these libraries are intended to be modular and not depend on each other's internal implementation details. But wallet code is still able to call node code indirectly through the `interfaces::Chain` abstract class in [`interfaces/chain.h`](../../src/interfaces/chain.h) and node code calls wallet code through the `interfaces::ChainClient` and `interfaces::Chain::Notifications` abstract classes in the same file. In general, defining abstract classes in [`src/interfaces/`](../../src/interfaces/) can be a convenient way of avoiding unwanted direct dependencies or circular dependencies between libraries.
 
 - *libbitcoin_consensus* should be a standalone dependency that any library can depend on, and it should not depend on any other libraries itself.
 

src/Makefile.am

@@ -346,11 +346,7 @@ obj/build.h: FORCE
 	  "$(abs_top_srcdir)"
 libbitcoin_util_a-clientversion.$(OBJEXT): obj/build.h
 
-
-# server: shared between bitcoind and bitcoin-qt
-# Contains code accessing mempool and chain state that is meant to be separated
-# from wallet and gui code (see node/README.md). Shared code should go in
-# libbitcoin_common or libbitcoin_util libraries, instead.
+# node #
 libbitcoin_node_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(BOOST_CPPFLAGS) $(MINIUPNPC_CPPFLAGS) $(NATPMP_CPPFLAGS) $(EVENT_CFLAGS) $(EVENT_PTHREADS_CFLAGS)
 libbitcoin_node_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_node_a_SOURCES = \
@@ -441,7 +437,9 @@ endif
 if !ENABLE_WALLET
 libbitcoin_node_a_SOURCES += dummywallet.cpp
 endif
+#
 
+# zmq #
 if ENABLE_ZMQ
 libbitcoin_zmq_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(ZMQ_CFLAGS)
 libbitcoin_zmq_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
@@ -452,10 +450,9 @@ libbitcoin_zmq_a_SOURCES = \
   zmq/zmqrpc.cpp \
   zmq/zmqutil.cpp
 endif
+#
 
-
-# wallet: shared between bitcoind and bitcoin-qt, but only linked
-# when wallet enabled
+# wallet #
 libbitcoin_wallet_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(BOOST_CPPFLAGS) $(BDB_CPPFLAGS) $(SQLITE_CFLAGS)
 libbitcoin_wallet_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_wallet_a_SOURCES = \
@@ -494,14 +491,17 @@ endif
 if USE_BDB
 libbitcoin_wallet_a_SOURCES += wallet/bdb.cpp wallet/salvage.cpp
 endif
+#
 
+# wallet tool #
 libbitcoin_wallet_tool_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(BOOST_CPPFLAGS)
 libbitcoin_wallet_tool_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_wallet_tool_a_SOURCES = \
   wallet/wallettool.cpp \
   $(BITCOIN_CORE_H)
+#
 
-# crypto primitives library
+# crypto #
 crypto_libbitcoin_crypto_base_la_CPPFLAGS = $(AM_CPPFLAGS)
 
 # Specify -static in both CXXFLAGS and LDFLAGS so libtool will only build a
@@ -581,8 +581,9 @@ crypto_libbitcoin_crypto_arm_shani_la_CPPFLAGS = $(AM_CPPFLAGS)
 crypto_libbitcoin_crypto_arm_shani_la_CXXFLAGS += $(ARM_SHANI_CXXFLAGS)
 crypto_libbitcoin_crypto_arm_shani_la_CPPFLAGS += -DENABLE_ARM_SHANI
 crypto_libbitcoin_crypto_arm_shani_la_SOURCES = crypto/sha256_arm_shani.cpp
+#
 
-# consensus: shared between all executables that validate any consensus rules.
+# consensus #
 libbitcoin_consensus_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 libbitcoin_consensus_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_consensus_a_SOURCES = \
@@ -618,8 +619,9 @@ libbitcoin_consensus_a_SOURCES = \
   util/strencodings.cpp \
   util/strencodings.h \
   version.h
+#
 
-# common: shared between bitcoind, and bitcoin-qt and non-server tools
+# common #
 libbitcoin_common_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(BOOST_CPPFLAGS)
 libbitcoin_common_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_common_a_SOURCES = \
@@ -658,8 +660,9 @@ libbitcoin_common_a_SOURCES = \
   script/standard.cpp \
   warnings.cpp \
   $(BITCOIN_CORE_H)
+#
 
-# util: shared between all executables.
+# util #
 libbitcoin_util_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(BOOST_CPPFLAGS)
 libbitcoin_util_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_util_a_SOURCES = \
@@ -707,8 +710,9 @@ libbitcoin_util_a_SOURCES = \
 if USE_LIBEVENT
 libbitcoin_util_a_SOURCES += util/url.cpp
 endif
+#
 
-# cli: shared between bitcoin-cli and bitcoin-qt
+# cli #
 libbitcoin_cli_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 libbitcoin_cli_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_cli_a_SOURCES = \