Update figure in HoVerNet pipeline (#1111)

part of #4882.

### Description
update figure in HoVerNet pipeline

### Checks
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [ ] Notebook runs automatically `./runner [-p <regex_pattern>]`

Signed-off-by: KumoLiu <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: KumoLiu

figures/hovernet_pipeline.png

@@ -3,7 +3,7 @@
 This folder contains ignite version examples to run train and validate a HoVerNet [1] model.
 It also has torch version notebooks to run training and evaluation.
 <p align="center">
-  <img src="https://ars.els-cdn.com/content/image/1-s2.0-S1361841519301045-fx1_lrg.jpg" alt="HoVerNet scheme")
+  <img src="../../figures/hovernet_pipeline.png" alt="HoVerNet scheme")
 </p>
 
 ### 1. Data