Correct lammps.book

doc/src/lammps.book

@@ -32,21 +32,21 @@ Modify_body.html
 Modify_thermo.html
 Modify_variable.html
 Python.html
-Python_overview.txt
-Python_run.txt
-Python_shlib.txt
-Python_install.txt
-Python_mpi.txt
-Python_test.txt
-Python_library.txt
-Python_pylammps.txt
-Python_examples.txt
-Python_call.txt
+Python_overview.html
+Python_run.html
+Python_shlib.html
+Python_install.html
+Python_mpi.html
+Python_test.html
+Python_library.html
+Python_pylammps.html
+Python_examples.html
+Python_call.html
 Errors.html
-Errors_common.txt
-Errors_bugs.txt
-Errors_messages.txt
-Errors_warnings.txt
+Errors_common.html
+Errors_bugs.html
+Errors_messages.html
+Errors_warnings.html
 Section_history.html
 
 lammps_tutorials.html