README.md in strong_migrations-1.3.2 vs README.md in strong_migrations-1.4.0

@@ -72,10 +72,11 @@
 Postgres-specific checks:
 
 - [adding an index non-concurrently](#adding-an-index-non-concurrently)
 - [adding a reference](#adding-a-reference)
 - [adding a foreign key](#adding-a-foreign-key)
+- [adding an exclusion constraint](#adding-an-exclusion-constraint)
 - [adding a json column](#adding-a-json-column)
 - [setting NOT NULL on an existing column](#setting-not-null-on-an-existing-column)
 
 Best practices:
 
@@ -105,22 +106,22 @@
   class User < ApplicationRecord
     self.ignored_columns = ["some_column"]
   end
   ```
 
-2. Deploy code
+2. Deploy the code
 3. Write a migration to remove the column (wrap in `safety_assured` block)
 
   ```ruby
   class RemoveSomeColumnFromUsers < ActiveRecord::Migration[7.0]
     def change
       safety_assured { remove_column :users, :some_column }
     end
   end
   ```
 
-4. Deploy and run migration
+4. Deploy and run the migration
 5. Remove the line added in step 1
 
 ### Adding a column with a default value
 
 #### Bad
@@ -485,9 +486,27 @@
   def change
     validate_foreign_key :users, :orders
   end
 end
 ```
+
+### Adding an exclusion constraint
+
+#### Bad
+
+In Postgres, adding an exclusion constraint blocks reads and writes while every row is checked.
+
+```ruby
+class AddExclusionContraint < ActiveRecord::Migration[7.1]
+  def change
+    add_exclusion_constraint :users, "number WITH =", using: :gist
+  end
+end
+```
+
+#### Good
+
+[Let us know](https://github.com/ankane/strong_migrations/issues/new) if you have a safe way to do this (exclusion constraints cannot be marked `NOT VALID`).
 
 ### Adding a json column
 
 #### Bad