Upgrade Documenter, and add make target to fix doctests (#26515)

* upgrade Documenter to v0.15.0

* add make target to fix all (outdated) doctests:

    make -C doc doctest-fix

doc/Makefile

@@ -8,15 +8,16 @@ JULIAHOME := $(abspath $(SRCDIR)/..)
 include $(JULIAHOME)/Make.inc
 JULIA_EXECUTABLE := $(call spawn,$(build_bindir)/julia)
 
-.PHONY: help clean cleanall html pdf linkcheck doctest check deps deploy
+.PHONY: help clean cleanall html pdf linkcheck doctest doctest-fix check deps deploy
 
 help:
  @echo "Please use 'make <target>' where <target> is one of"
- @echo " html to make standalone HTML files"
- @echo " pdf to make standalone PDF file"
- @echo " linkcheck to check all external links for integrity"
- @echo " doctest to run all doctests embedded in the documentation"
- @echo " check to run linkcheck and doctests"
+ @echo " html to make standalone HTML files"
+ @echo " pdf to make standalone PDF file"
+ @echo " linkcheck to check all external links for integrity"
+ @echo " doctest to run all doctests embedded in the documentation"
+ @echo " doctest-fix to update all doctests embedded in the documentation"
+ @echo " check to run linkcheck and doctests"
 
 UnicodeData.txt:
  $(JLDOWNLOAD) http:https://www.unicode.org/Public/9.0.0/ucd/UnicodeData.txt
@@ -55,6 +56,11 @@ doctest: deps
  $(JULIA_EXECUTABLE) --color=yes $(call cygpath_w,$(SRCDIR)/make.jl) -- doctest
  @echo "Checks finished."
 
+doctest-fix: deps
+ @echo "Updating all embedded 'doctests'."
+ $(JULIA_EXECUTABLE) --color=yes $(call cygpath_w,$(SRCDIR)/make.jl) -- doctest-fix
+ @echo "Update finished."
+
 check: deps
  @echo "Running all embedded 'doctests' and checking external links."
  $(JULIA_EXECUTABLE) --color=yes $(call cygpath_w,$(SRCDIR)/make.jl) -- doctest linkcheck

doc/REQUIRE

@@ -1,3 +1,3 @@
-Compat 0.56.0 0.56.0+
+Compat 0.58.0 0.58.0+
 DocStringExtensions 0.4.3 0.4.3+
-Documenter 0.14.0 0.14.0+
+Documenter 0.15.0 0.15.0+

doc/make.jl

@@ -150,7 +150,7 @@ makedocs(
  build = joinpath(@__DIR__, "_build/html/en"),
  modules = [Base, Core, BuildSysImg, [Base.root_module(Base, stdlib.stdlib) for stdlib in STDLIB_DOCS]...],
  clean = true,
- doctest = "doctest" in ARGS,
+ doctest = ("doctest-fix" in ARGS) ? (:fix) : ("doctest" in ARGS),
  linkcheck = "linkcheck" in ARGS,
  linkcheck_ignore = ["https://bugs.kde.org/show_bug.cgi?id=136779"], # fails to load from nanosoldier?
  strict = false,