Reducing the verbosity of the tutorial

[ConnorWelch-OSU]

Summary of Changes

This PR address the verbosity of the tutorial identified in #442. To reduce verbosity, repeated examples of XML blocks were removed, leaving only a template for each section of an input file. Additionally, minor changes to the text around where XML blocks were removed has been edited to fit the new context that it exists in.

Design Notes

I did not remove the XML blocks that users can use to check that their input files are correct that are at the end of some pages. There is a discussion to be had on whether these are something that we want to keep or not.

Check the box if your change does not break any of the following:

• API for Cyclus modules
• Input files
• Output tables for post processing tools

Related CEPs and Issues

Fixes #442

Associated Developers

Testing and Validation

• I have read the Contributing to Cyclus guide
• I have compiled and run the code locally
• I have added or updated relevant tests
• I have added documentation for new or changed features
• This code follows the style guide
• I have updated the changelog

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