Update feature templates (#22)

Update feature templates

Author: denis-fokin

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,38 @@
+---
+name: Feature request
+about: Suggest an idea for the UTBot project
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Description**
+
+_Substitute this text with a concise description of the problem. Please be clear what parts of the problem are considered to be in-scope and out-of-scope._
+
+_Example:_ Sometimes engine does not emit any tests. Seems that in such situations we can use a fuzzer.
+
+**Expected behavior**
+
+_Substitute the text with a clear and concise description of what you want to happen._
+
+_Example:_ We can significantly improve coverage with a smart fuzzer. We can not only feed the API under test with a corner case data but analyze the control-flows graph in order to find additional data to fuzz.
+
+**Environment**
+
+_Substitute the text with steps to set up the environment for testing of the expected behavior._ 
+
+_Example:_ You can execute test generation for a complex example. Stop the generation in several seconds after the start.
+
+**Potential alternatives**
+
+_Substitute this text with a potential alternative to the solution._
+
+_Example:_ We can use simpler version of a fuzzer that just finds corner cases for primitives.
+
+**Context**
+
+_Substitute this text with information that can be crucial for understanding the problem._
+
+_Example:_ fuzzing is the process of providing invalid, unexpected, or random data to a computer program. In context of UTBot, we are going to provide the data to the API under test.