[depr.filesystems] Introduced section to group filesystems deprecations

Author: AlisdairM

source/future.tex

@@ -762,7 +762,9 @@
 Equivalent to: \tcode{return visit(std::forward<Visitor>(vis), arg.value);}
 \end{itemdescr}
 
-\rSec1[depr.fs.path.factory]{Deprecated filesystem path factory functions}
+\rSec1[depr.filesystems]{Deprecated file systems}
+
+\rSec2[depr.fs.path.factory]{Deprecated filesystem path factory functions}
 
 \pnum
 The header \libheaderrefx{filesystem}{fs.filesystem.syn} has the following additions:
@@ -841,7 +843,7 @@
 \end{note}
 \end{itemdescr}
 
-\rSec1[depr.fs.path.obs]{Deprecated filesystem path format observers}
+\rSec2[depr.fs.path.obs]{Deprecated filesystem path format observers}
 
 \indexlibraryglobal{path}%
 \pnum