update ldc2d doc

Author: HydrogenSulfate

docs/zh/examples/ldc2d_steady.md

@@ -8,7 +8,7 @@
 
         ``` sh
         # linux
-        wget -P ./data/ \
+        wget -nc -P ./data/ \
             https://paddle-org.bj.bcebos.com/paddlescience/datasets/ldc/ldc_Re100.mat \
             https://paddle-org.bj.bcebos.com/paddlescience/datasets/ldc/ldc_Re400.mat \
             https://paddle-org.bj.bcebos.com/paddlescience/datasets/ldc/ldc_Re1000.mat \
@@ -25,7 +25,7 @@
 
         ``` sh
         # linux
-        wget -P ./data/ https://paddle-org.bj.bcebos.com/paddlescience/datasets/ldc/ldc_Re1000.mat
+        wget -nc -P ./data/ https://paddle-org.bj.bcebos.com/paddlescience/datasets/ldc/ldc_Re1000.mat
         # windows
         # curl https://paddle-org.bj.bcebos.com/paddlescience/datasets/ldc/ldc_Re1000.mat --create-dirs -o ./data/ldc_Re1000.mat
         python ldc_2d_Re3200_sota.py mode=eval EVAL.pretrained_model_path=https://paddle-org.bj.bcebos.com/paddlescience/models/ldc/ldc_re1000_sota_pretrained.pdparams
@@ -41,7 +41,7 @@
 
         ``` sh
         # linux
-        wget -P ./data/ https://paddle-org.bj.bcebos.com/paddlescience/datasets/ldc/ldc_Re1000.mat
+        wget -nc -P ./data/ https://paddle-org.bj.bcebos.com/paddlescience/datasets/ldc/ldc_Re1000.mat
         # windows
         # curl https://paddle-org.bj.bcebos.com/paddlescience/datasets/ldc/ldc_Re1000.mat --create-dirs -o ./data/ldc_Re1000.mat
         python ldc_2d_Re3200_sota.py mode=infer

examples/ldc/conf/ldc_2d_Re3200_piratenet.yaml

@@ -82,7 +82,7 @@ EVAL:
 
 # inference settings
 INFER:
-  pretrained_model_path: null
+  pretrained_model_path: https://paddle-org.bj.bcebos.com/paddlescience/models/ldc/ldc_re3200_piratenet_pretrained.pdparams
   export_path: ./inference/ldc_2d_re3200
   pdmodel_path: ${INFER.export_path}.pdmodel
   pdiparams_path: ${INFER.export_path}.pdiparams