Update README.md: add 'abacus/stru' format key (#392)

add 'abacus/stru' format key

Signed-off-by: LiangWenshuo1118 <[email protected]>

Author: LiangWenshuo1118

README.md

@@ -80,6 +80,7 @@ The `System` or `LabeledSystem` can be constructed from the following file forma
 | Amber   | multi       | True         | True    | LabeledSystem | 'amber/md'           |
 | Amber/sqm | sqm.out   | False        | False   | System        | 'sqm/out'            |
 | Gromacs | gro         | True         | False   | System        | 'gromacs/gro'        |
+| ABACUS  | STRU        | False        | False   | System        | 'abacus/stru'         |
 | ABACUS  | STRU        | False        | True    | LabeledSystem | 'abacus/scf'         |
 | ABACUS  | cif         | True         | True    | LabeledSystem | 'abacus/md'          |
 | ABACUS  | STRU        | True         | True    | LabeledSystem | 'abacus/relax'       |