Fix chart alts in Readme

Change-Id: I02a5208a2cd90e36a542a42ecd2ab9ba3b377af1
diff --git a/Readme.md b/Readme.md
index ca7f5d4..3aa05cc 100644
--- a/Readme.md
+++ b/Readme.md
@@ -14,8 +14,9 @@
 
 ### Tokens per ICC genre
 
-![graph](https://gitlab.ids-mannheim.de/ICC/2023-07-20-ICC-ICLC10/-/jobs/artifacts/master/raw/target/tokens_per_genre.png?job=build-job)
+![tokens per ICC genre](https://gitlab.ids-mannheim.de/ICC/2023-07-20-ICC-ICLC10/-/jobs/artifacts/master/raw/target/tokens_per_genre.png?job=build-job)
 
 ### Tokens per year
 
-![graph](https://gitlab.ids-mannheim.de/ICC/2023-07-20-ICC-ICLC10/-/jobs/artifacts/master/raw/target/tokens_per_year.png?job=build-job)
+![tokens per year](https://gitlab.ids-mannheim.de/ICC/2023-07-20-ICC-ICLC10/-/jobs/artifacts/master/raw/target/tokens_per_year.png?job=build-job)
+