.gitignore: Remove redundant rules on result*, target

From man gitignore:

    A leading "**" followed by a slash means match in all directories.
    For example, "**/foo" matches file or directory "foo" anywhere, the
    same as pattern "foo".

In other words, we don't need "/target/**" in the .gitignore if we
already have "**/target/**". Same applies to "/result*". Let's remove
the redundant rules.

Also sort the file alphabetically (as per Vim's ":%s").

Signed-off-by: Quentin Monnet <[email protected]>

.gitignore

@@ -1,10 +1,8 @@
 **/result*/**
 **/target/**
-/result*
-/target/**
+/.bin/**
+/.vscode/**
+/compile-env/**
 /design-docs/src/mdbook/book/**
 /design-docs/src/mdbook/src/mdbook-plantuml-img/**
-/compile-env/**
-/.vscode/**
-/.bin/**
 /dev-env-template/**