Update README.md (#913)

Use full URL for migration journey

Author: arriolac

README.md

@@ -2,7 +2,7 @@
 
 A gardening app illustrating Android development best practices with migrating a View-based app to
 Jetpack Compose. To learn about how Sunflower was migrated to Compose, see the 
-[migration journey](docs/MigrationJourney.md) document.
+[migration journey](https://github.com/android/sunflower/blob/main/docs/MigrationJourney.md) document.
 
 **Note**: To see the original View implementation of Sunflower, checkout the [`views`](https://github.com/android/sunflower/tree/views) branch.
 
@@ -86,4 +86,4 @@ Third Party Content
 -------------------
 Select text used for describing the plants (in `plants.json`) are used from Wikipedia via CC BY-SA 3.0 US (license in `ASSETS_LICENSE`).
 
-"[seed](https://thenounproject.com/search/?q=seed&i=1585971)" by [Aisyah](https://thenounproject.com/aisyahalmasyira/) is licensed under [CC BY 3.0](https://creativecommons.org/licenses/by/3.0/us/legalcode)
+"[seed](https://thenounproject.com/search/?q=seed&i=1585971)" by [Aisyah](https://thenounproject.com/aisyahalmasyira/) is licensed under [CC BY 3.0](https://creativecommons.org/licenses/by/3.0/us/legalcode)