user-guide: review "Managing External Data" examples

[jorgeorpinel]

Per request from @MrOutis in treeverse/dvc#2092 (comment)

See doc in question: https://dvc.org/doc/user-guide/managing-external-data#examples (SSH)

This part specifically for example may not make sense:

# Add SSH remote to be used as cache location for SSH files
dvc remote add sshcache ssh://user@example.com:/cache

# Tell dvc to use the 'sshcache' remote as SSH cache location
dvc config cache.ssh sshcache

# Add data on SSH directly
dvc add ssh://user@example.com:/mydata

Because the sshcache remote name is never used.

• Also, the paths used in SSH URIs throughout don't match (:/cache vs :/mydata vs :/home/shared/data.txt).

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Related to #143

[jorgeorpinel]

Because the sshcache remote name is never used.

I don't think that's correct actually. The remote is registered and then configured as the SSH cache.

The paths are strange though, not only because :/cache vs :/mydata don't match, but because of the way dvc add is used. For example:

# Add data on SSH directly
dvc add ssh://user@example.com:/mydata

• What does adding a URL do? I don't think you can even do that. At least it's not explained in https://dvc.org/doc/commands-reference/add

[jorgeorpinel]

Another note to add to this document (and to the external dependencies one) is that SSH remote locations (and soon others) now support adding entire directories. See treeverse/dvc#1654 (comment).

[efiop]

Also now directories are supported for s3 too treeverse/dvc#2619