Create TROUBLESHOOTING.md (Significant-Gravitas#5300)

TROUBLESHOOTING.md

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+This page is a list of issues you could encounter along with their fixes.
+
+# Frontend
+**Github Authentication**
+
+Error during GitHub Sign-In: [firebase_auth/account-exists-with-different-credential]
+An account already exists with the same email address but different sign-in
+credentials. Sign in using a provider associated with this email address.
+
+*Solution*
+
+Reset the frontend folder
+go to the root of the repository
+
+```
+rm -rf frontend
+git checkout origin/master frontend
+```
+---
+<!-- Add other change here -->
+
+# Forge
+TODO
+
+### Benchmark
+TODO