Update gsoc-project.md to add issue label

Use h2 headers rather than bold

.github/ISSUE_TEMPLATE/gsoc-project.md

@@ -2,37 +2,32 @@
 name: GSoC Project Idea
 about: "Project idea for students applying to Google Summer of Code"
 title: ''
-labels: 'GSoC'
+labels: 'gsoc-idea'
 assignees: ''
-
 ---
 
 <!-- Please feel free to propose your own project using this template. Cantera developers will assist in refining the project idea once the issue is created. -->
 
-**Idea**
+## Idea
 
 <!-- A brief description of the project. Make sure to address:
 
 * What problem is it trying to solve?
 * What are possible solutions?
 -->
 
-
-**Difficulty**
+## Difficulty
 
 <!-- Provide your best estimate at difficulty level: e.g. Easy / Medium / Hard -->
 
-
-**Required Knowledge**
+## Required Knowledge
 
 <!-- Provide details on required knowledge: e.g. Python / C++ / etc. -->
 
-
-**Mentors**
+## Mentors
 
 <!-- Github handle of project mentor -->
 
-
-**References**
+## References
 
 <!-- Links to related Pull Requests, GitHub Issues, Users' Group topics, or other relevant material. -->