docs: move delete methods to implemented

Author: machow

docs/api/boards.rst

@@ -23,6 +23,9 @@ Methods (Implemented)
    ~BaseBoard.pin_versions
    ~BaseBoard.pin_list
    ~BaseBoard.pin_exists
+   ~BaseBoard.pin_version_delete
+   ~BaseBoard.pin_versions_prune
+   ~BaseBoard.pin_delete
 
 Methods (Planned)
 -----------------
@@ -31,8 +34,5 @@ Methods (Planned)
 
    ~BaseBoard.pin_download
    ~BaseBoard.pin_upload
-   ~BaseBoard.pin_version_delete
-   ~BaseBoard.pin_versions_prune
    ~BaseBoard.pin_search
-   ~BaseBoard.pin_delete
    ~BaseBoard.pin_browse