misc: Add bug report template (#85)

* misc: Add Bug Report Issue Template

Change-Id: I3acf7a1991f889462c0f2604d251dead563846c2

* misc: Cleanup bug_report.md

* Inform the reader to use codeblocks where approproate.
* Inform the reader they should include the Python configuraiton
  script and state parameters passed.

Change-Id: Ib0b8e9a6d3ed199c435917acfdf958073d4faa04

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,62 @@
+---
+name: Bug report
+about: Create a report to help us find and fix the bug
+title: ''
+labels: bug
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**Affects version**
+State which version of gem5 this bug was found in. If on the develop branch state the Commit revision ID you are working.
+
+**gem5 Modifications**
+If you have modified gem5 in some way please state, to the best of your ability, how it has been modified.
+
+**To Reproduce**
+Steps to reproduce the behavior. Please assume starting from a clean repository:
+1. Compile gem5 with command ...
+2. Execute the simulation with...
+
+If writing code, or a terminal command, use code blocks. Either an inline code block, \`scons build/ALL/gem5.opt\` (enclosed in two \`) or a multi-line codeblock:
+
+
+\`\`\`
+
+int x=2;
+
+int y=3'
+
+print(x+y);
+
+\`\`\`
+
+If possible, please include the Python configuration script used and state clearly any parameters passed.
+
+**Terminal Output**
+If applicable, add the terminal output here. If long, only include the relevant lines.
+Please put the terminal output in code blocks. I.e.:
+
+\`\`\`
+
+#Terminal output here#
+
+\`\`\`
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Host Operating System**
+Ubuntu 22.04, Mac OS X, etc.
+
+**Host ISA**
+ARM, X86, RISC-V, etc.
+
+**Compiler used**
+State which compiler was used to compile gem5. Please include the compiler version.
+
+**Additional information**
+Add any other information which does not fit in the previous sections but may be of use in fixing this bug.