fix errata in voc doc (openvinotoolkit#1163)

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### Summary
Color values in the labelmap.txt should be separated by commas, not
colons.

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Resolves openvinotoolkit#111 and openvinotoolkit#222.
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CHANGELOG.md

@@ -18,6 +18,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Enhance Datumaro data format stream importer performance
   (<https://github.com/openvinotoolkit/datumaro/pull/1153>)
 
+### Bug fixes
+- Fix errata in the voc document. Color values in the labelmap.txt should be separated by commas, not colons.
+  (<https://github.com/openvinotoolkit/datumaro/pull/1162>)
+
 ## 15/09/2023 - Release 1.5.0
 ### New features
 - Add tabular data import/export

docs/source/docs/data-formats/formats/pascal_voc.md

@@ -114,7 +114,7 @@ for example:
 ```
 # label_map [label : color_rgb : parts : actions]
 helicopter:::
-elephant:0:124:134:head,ear,foot:
+elephant:0,124,134:head,ear,foot:
 ```
 It is also possible to import grayscale (1-channel) PNG masks.
 For grayscale masks provide a list of labels with the number of lines