Add suggestions to mention sourcing env.fish

Author: rami3l

src/cli/self_update.rs

@@ -225,13 +225,12 @@ This would reload your `PATH` environment variable to include
 Cargo's bin directory ({cargo_home}/bin).
 
 To configure your current shell, you need to source
-the `env` file ({cargo_home}/env).
+the corresponding `env` file under {cargo_home}.
 
-This is usually done by running:
-    source "{cargo_home}/env"
-
-The `source` command above might need to be replaced with `.`
-on shells like `ash`, `dash` and `pdksh`.
+This is usually done by running one of the following:
+    source "{cargo_home}/env"        # For bash/zsh
+    . "{cargo_home}/env"             # For ash/dash/pdksh (note the leading DOT)
+    source "{cargo_home}/env.fish"   # For fish
 "#
     };
 }
@@ -258,13 +257,12 @@ To get started you need Cargo's bin directory ({cargo_home}/bin) in your `PATH`
 environment variable. This has not been done automatically.
 
 To configure your current shell, you need to source
-the `env` file ({cargo_home}/env).
-
-This is usually done by running:
-    source "{cargo_home}/env"
+the corresponding `env` file under {cargo_home}.
 
-The `source` command above might need to be replaced with `.`
-on shells like `ash`, `dash` and `pdksh`.
+This is usually done by running one of the following:
+    source "{cargo_home}/env"        # For bash/zsh
+    . "{cargo_home}/env"             # For ash/dash/pdksh (note the leading DOT)
+    source "{cargo_home}/env.fish"   # For fish
 "#
     };
 }