Merge branch 'js/misc-doc-fixes'

"make check-docs", "git help -a", etc. did not account for cases
where a particular build may deliberately omit some subcommands,
which has been corrected.

* js/misc-doc-fixes:
  Turn `git serve` into a test helper
  test-tool: handle the `-C <directory>` option just like `git`
  check-docs: do not bother checking for legacy scripts' documentation
  docs: exclude documentation for commands that have been excluded
  check-docs: allow command-list.txt to contain excluded commands
  help -a: do not list commands that are excluded from the build
  Makefile: drop the NO_INSTALL variable
  remote-testgit: move it into the support directory for t5801

t/t5702-protocol-v2.sh

@@ -400,12 +400,13 @@ test_expect_success 'even with handcrafted request, filter does not work if not
 	0000
 	EOF
 
-	test_must_fail git -C server serve --stateless-rpc <in >/dev/null 2>err &&
+	test_must_fail test-tool -C server serve-v2 --stateless-rpc \
+		<in >/dev/null 2>err &&
 	grep "unexpected line: .filter blob:none." err &&
 
 	# Exercise to ensure that if advertised, filter works
 	git -C server config uploadpack.allowfilter 1 &&
-	git -C server serve --stateless-rpc <in >/dev/null
+	test-tool -C server serve-v2 --stateless-rpc <in >/dev/null
 '
 
 test_expect_success 'default refspec is used to filter ref when fetchcing' '