Merge #116: doc: fix link to optimize-pngs.py script

cca1acf doc: fix link to optimize-pngs.py script (Jarol Rodriguez)

Pull request description:

  Fix the link to the [optimize-pngs.py](https://github.com/bitcoin-core/bitcoin-maintainer-tools/blob/main/optimize-pngs.py) script mentioned in our icon policy documentation.

ACKs for top commit:
  hebasto:
    ACK cca1acf, tested a fixed link.

Tree-SHA512: 893d3f101d1601199902260e8d683408ee2fbd8d792a3041a81263b9e060f31d4e8d4e071c881370dcfe9a3d22107032c73ff7c60316c1875069f4481eafcb9c

Author: hebasto

src/qml/doc/icon-policy.md

@@ -17,7 +17,7 @@ PNGs are used in production due to wide application support, transparency suppor
 and better image quality compared to competing file types such as JPEG.
 
 #### Optimizing Production Files (PNG)
-Production (PNG) files must be processed by the [optimize-png.py](https://github.com/bitcoin-core/bitcoin-maintainer-tools/blob/master/optimise-pngs.py) script before their inclusion in Bitcoin Core.
+Production (PNG) files must be processed by the [optimize-pngs.py](https://github.com/bitcoin-core/bitcoin-maintainer-tools/blob/master/optimize-pngs.py) script before their inclusion in Bitcoin Core.
 PNG optimization removes various unnecessary color profiles, ancillary data,
 and text chunks, resulting in a lossless file size reduction.