make references consistent

doc/src/Howto_lammps_gui.rst

@@ -16,7 +16,7 @@ adapted in multiple ways specifically for editing LAMMPS input files.
    Pre-compiled, ready-to-use LAMMPS GUI executables for Linux (Ubuntu
    20.04LTS or later and compatible), macOS (version 11 aka Big Sur or
    later), and Windows (version 10 or later) :ref:`are available
-   <lammps-gui-install>` for download.  The executables are linked to
+   <lammps_gui_install>` for download.  The executables are linked to
    a current version of LAMMPS as well.  The source code for the
    LAMMPS GUI is included in the ``tools/lammps-gui`` folder of the
    LAMMPS distribution and it can be compiled alongside LAMMPS with

doc/src/Intro_nonfeatures.rst

@@ -26,7 +26,7 @@ Here are suggestions on how to perform these tasks:
   written in Python or C/C++ that run LAMMPS and visualize or plot its
   output.  Examples of this are provided in the python directory and
   described on the :doc:`Python <Python_head>` doc page.  As of version
-  2 August 2023 :ref:`a GUI tool <lammps-gui>` is included in LAMMPS.
+  2 August 2023 :ref:`a GUI tool <lammps_gui>` is included in LAMMPS.
   Also, there are several external wrappers or GUI front ends.
 * **Builder:** Several pre-processing tools are packaged with LAMMPS.
   Some of them convert input files in formats produced by other MD codes

doc/src/Tools.rst

@@ -706,7 +706,7 @@ required.  The LAMMPS GUI has been successfully compiled and tested on:
 - Windows 10 and 11 x86_64 with Visual Studio 2022 and Visual C++ 14.36, Qt version 5.15LTS
 - Windows 10 and 11 x86_64 with MinGW / GCC 10.0 cross-compiler on Fedora 38, Qt version 5.15LTS
 
-.. _lammps-gui-install:
+.. _lammps_gui_install:
 
 
 Pre-compiled executables