The Copyright section specifies additional conditions, so the License
header is not correct (or at least misleading). So let's just remove it.
This is pragmatic because the field was only added as part of the
activation of BIP 2 anyway, and there are other old BIPs with a License
header.
```
sed -z -i 's/Author: /Authors: /' bip-0*.md
sed -z -i 's/Author: /Authors: /' bip-0*.mediawiki
```
Also align correctly in case of multiple authors.
```
sed -z -i 's/Type: Standards Track/Type: Specification/' bip-0*.md
sed -z -i 's/Type: Standards Track/Type: Specification/' bip-0*.mediawiki
```
After the scripted changes, the changes to BIP-40, BIP-41, and BIP-63
were undone, because it breaks CI.
These three BIPs only exist conceptually and their proposal documents
are missing which causes changes to them ot break the CI. I defer the
changes to these BIPs to a separate pull request to get CI to pass.
- Update all Accepted status to Proposed (renamed status)
- The BIP Comments preamble headers added to every BIP
- The License preamble headers have been added to all BIPs with a Copyright section
