doc: introduces short namespace absence proof in the NMT specs

[staheri14]

Overview

Closes #205 Additionally, in line with this, to ensure consistency with how namespace ID and namespace (i.e., a combination of namespace ID and version) are utilized in the core-app, I have replaced all instances of words that refer to or imply namespace ID with the more accurate term "namespace".

Checklist

• [x] New and updated code has appropriate documentation
• [x] New and updated code has new and/or updated testing
• [x] Required CI checks are passing
• [x] Visual proof for any user facing features like CLI or documentation updates
• [x] Linked issues closed with keywords

[codecov[bot]]

Codecov Report

Merging #209 (5946b91) into master (cdc88e8) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #209   +/-   ##
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  Coverage   94.03%   94.03%           
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  Files           5        5           
  Lines         570      570           
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  Hits          536      536           
  Misses         19       19           
  Partials       15       15           

[rootulp]

Closes https://github.com/celestiaorg/nmt/issues/206

[staheri14]

Overall LGTM, thanks for addressing #206

I think we may want to also rename

https://github.com/celestiaorg/nmt/blob/cdc88e891d11878dc8b63447e01706d746791b14/namespace/id.go#L8

but that could be a follow up

Sure, thanks for mentioning it, I will take care of the code change as well, however, as this will constitute a breaking change, it deserves a separate PR.

[cmwaters]

Overall LGTM, thanks for addressing #206

I think we may want to also rename

https://github.com/celestiaorg/nmt/blob/cdc88e891d11878dc8b63447e01706d746791b14/namespace/id.go#L8

but that could be a follow up

If we do, I don't think it needs to remain in its own package. It should just be nmt.Namespace

[staheri14]

Overall LGTM, thanks for addressing #206 I think we may want to also rename https://github.com/celestiaorg/nmt/blob/cdc88e891d11878dc8b63447e01706d746791b14/namespace/id.go#L8

but that could be a follow up

If we do, I don't think it needs to remain in its own package. It should just be nmt.Namespace

Thanks for your comment, I noted this in its respective issue.

[staheri14]

Going to merge this PR, but will be monitoring this PR for addressing your questions and comments.