[gegl] docs: tidy up heading levels

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 132f01fac796a303c0e2ba64423969a372949bf6
Author: John Marshall <jtm home gmail com>
Date:   Thu Jul 9 19:00:22 2020 +0100

    docs: tidy up heading levels

 docs/copyright.txt.in | 2 +-
 docs/environment.txt  | 9 +++++----
 2 files changed, 6 insertions(+), 5 deletions(-)
---
diff --git a/docs/copyright.txt.in b/docs/copyright.txt.in
index c2a056ed0..af7c88b0f 100644
--- a/docs/copyright.txt.in
+++ b/docs/copyright.txt.in
@@ -1,5 +1,5 @@
 Copyright
-~~~~~~~~~
+---------
 GEGL is free software; you can redistribute it and/or modify it under the terms
 of the link:LGPL[GNU Lesser General Public License] and link:GPL[GNU General
 Public License] as published by the Free Software Foundation; either version 3
diff --git a/docs/environment.txt b/docs/environment.txt
index 188d02345..562429229 100644
--- a/docs/environment.txt
+++ b/docs/environment.txt
@@ -1,5 +1,6 @@
 Environment
-~~~~~~~~~~~
+-----------
+
 Some environment variables can be set to alter how GEGL runs, these options are
 also available as properties on a singleton GObject returned from gegl_config
 (). The defaults should be what one normally uses - overriding 
@@ -29,13 +30,13 @@ GEGL_DEBUG_RECTS::
     Show the results of have/need rect negotiations.
 GEGL_DEBUG_TIME::
     Print a performance instrumentation breakdown of GEGL and it's operations.
-GEGL_USE_OPENCL:
+GEGL_USE_OPENCL::
     Enable use of OpenCL processing.
-GEGL_PATH:
+GEGL_PATH::
     The directory where GEGL looks (recursively) for loadable operations,
     setting it to GEGL_PATH=/home/user/where_you_keep_src/gegl/operations
     permits running an application against the operations in the source dir
     instead of having to install the operations.
-BABL_PATH:
+BABL_PATH::
     The directory containing babl extensions, both new pixel formats/color
     models as well as fast-paths for efficient pixel format conversions.