Rollup merge of #70735 - GuillaumeGomez:cleanup-e0502, r=Dylan-DPC

Dylan-DPC · web-flow · commit 8100c5509b6d · 2020-04-03T19:35:56.000+02:00
Clean up E0502 explanation r? @Dylan-DPC
diff --git a/src/librustc_error_codes/error_codes/E0502.md b/src/librustc_error_codes/error_codes/E0502.md
@@ -1,5 +1,4 @@
-This error indicates that you are trying to borrow a variable as mutable when it
-has already been borrowed as immutable.
+A variable already borrowed as immutable was borrowed as mutable.
 
 Erroneous code example:
 
