DOC: Fix synthax of aliases list for pygmt.grdcut (#4059)

Fix indent - add white space for alises list

Author: yvonnefroehlich

pygmt/src/grdcut.py

@@ -52,7 +52,7 @@ def grdcut(
     Full GMT docs at :gmt-docs:`grdcut.html`.
 
     {aliases}
-      - J = projection
+       - J = projection
 
     Parameters
     ----------