[Sol->Yul] Adding documentation section about breaking changes when using ir

Co-authored-by: chriseth <chris@ethereum.org>

docs/conf.py

@@ -85,7 +85,7 @@ else:
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
-exclude_patterns = ['_build', 'contracts', 'types', 'examples', 'grammar']
+exclude_patterns = ['_build', 'contracts', 'types', 'examples', 'grammar', 'ir']
 
 # The reST default role (used for this markup: `text`) to use for all
 # documents.

docs/ir/ir-breaking-changes.rst

@@ -0,0 +1,6 @@
+********************************
+Solidity IR-based Codegen Changes
+********************************
+
+This section highlights the main differences between the old and the IR-based codegen,
+along with the reasoning behind the changes and how to update affected code.