master --> main changes

Author: computron

docs_rst/fireworks.tests.rst

@@ -4,10 +4,10 @@ fireworks.tests package
 Submodules
 ----------
 
-fireworks.tests.master\_tests module
+fireworks.tests.main\_tests module
 ------------------------------------
 
-.. automodule:: fireworks.tests.master_tests
+.. automodule:: fireworks.tests.main_tests
    :members:
    :undoc-members:
    :show-inheritance:

docs_rst/guide_to_writing_firetasks.rst

@@ -7,7 +7,7 @@ This guide covers in more detail how one can write their own Firetasks (and retu
 A "Hello World Example"
 =======================
 
-If you'd like to see a "Hello World" Example of a custom Firetask, you can go `here <https://github.com/materialsproject/fireworks/tree/master/fireworks/examples/custom_firetasks/hello_world>`_.
+If you'd like to see a "Hello World" Example of a custom Firetask, you can go `here <https://github.com/materialsproject/fireworks/tree/main/fireworks/examples/custom_firetasks/hello_world>`_.
 
 If you are able to run that example and want more details of how to modify and extend it, read on...
 

docs_rst/index.rst

@@ -262,7 +262,7 @@ Want to see something added or changed? There are many ways to make that a reali
 
 Please submit questions, issues / bug reports, and all other communication through the `FireWorks Discourse forum <https://discuss.matsci.org/c/fireworks>`_.
 
-Make contributions through GitHub using our `Contribution Guidelines. <https://github.com/materialsproject/fireworks/blob/master/CONTRIBUTING.md>`_
+Make contributions through GitHub using our `Contribution Guidelines. <https://github.com/materialsproject/fireworks/blob/main/CONTRIBUTING.md>`_
 
 The list of contributors to FireWorks can be found :doc:`here </contributors>`.