macros: adjust forge{auto,}setup macros to reflect current practice

forgeautosetup is utilized by almost 300 packages and is generally
useful for single-source specfiles — i.e., the large majority of cases —
so there are no plans to remove it.
For non-forge packages, the default in Fedora is to use `%autosetup` so
patches are automatically applied; it makes sense to adopt the same
practice for the forge macros.

rpm/macros.d/macros.forge

@@ -42,6 +42,8 @@ end
 }
 
 # Unpacks sources computed by %forgemeta
+#   - In most cases, it is recommended to instead use `%forgeautosetup -p1` so
+#     patches are automatically applied.
 # Control variables, flags and arguments:
 #   %{forgesource<number>}       the source archive that will be processed
 #   %{forgesetupargs<number>}    %setup arguments
@@ -63,8 +65,12 @@ end
 }
 
 # Calls %autosetup using %forgemeta results
-#   – this will probably be removed since it is unsafe in presence of multiple
-#     sources
+#   – Using %forgeautosetup is not recommended in specfiles with multiple
+#     %forgeurl definitions,
+#     as %autosetup may produce strange results with multiple sources present.
+#     If you have have muiltiple sources,
+#     you can use `%forgesetup -a` to unpack them all at once and then apply
+#     patches manually using the %patch macro.
 # Control variables, flags and arguments:
 #   -z <number>  process the zth block of definitions
 #   -v -N -S -p  relayed to %autosetup