Creates I2I template

.github/ISSUE_TEMPLATE/intent-to-implement--i2i-.md

@@ -0,0 +1,42 @@
+---
+name: Intent-to-implement (I2I)
+about: Proposes a significant change/update to AMP.  See https://github.com/ampproject/amphtml/blob/master/CONTRIBUTING.md.
+title: 'I2I: <your feature/change>'
+labels: INTENT TO IMPLEMENT
+assignees: ''
+
+---
+
+<!---
+Replace/remove all of the text in brackets, including this text.
+
+See https://github.com/ampproject/amphtml/blob/master/CONTRIBUTING.md for help determining if you need to file an I2I for your change/fix, instructions on filling out this I2I template and how to get help if you have questions.  Note that If you are implementing a minor change/fix, you likely do not need to file this I2I.
+-->
+
+**Summary**
+<!---
+Provide a brief description of the feature/change you are planning on implementing.
+-->
+
+**Design document**
+<!---
+Provide a link to your design document once you have one.  You do not need a design document to file this I2I.
+-->
+
+**Motivation**
+<!---
+Explain why AMP needs this change. It may be useful to describe what AMP developers/users are forced to do without it. When possible, include links to back up your claims.
+-->
+
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+<!---
+Add any other information that may help people understand your I2I.
+-->
+
+<!---
+Add anyone to this cc line that you want to notify about this I2I, including a reviewer once you have found one.  (See https://github.com/ampproject/amphtml/blob/master/CONTRIBUTING.md for help in finding a reviewer.)
+-->
+
+/cc @ampproject/wg-approvers