New review comment by ericonr on void-packages repository

https://github.com/void-linux/void-packages/pull/26950#discussion_r539750677

Comment:
```suggestion
    # sed supports comment but let's put them here
    # 1: print everything between pairs of <""> in subpackages[+]?="..."
    # 2: multiline subpackages="...\n..."
    # 2.1: For any line in the middle, i.e., no <"> exists, print it
    # 2.2: For the first line, print everything after <">
    # 2.3: For last line, print everything before <">
```