Misleading info in User's Guide concerning restrictions to the yaml_metadata_block extension

[YvesMarcoux]

The User's Guide contains the following paragraphs in the section on yaml_metadata_block extension (end of the section):

Note: the yaml_metadata_block extension works with commonmark as well as markdown (and it is enabled by default in gfm and commonmark_x). However, in these formats the following restrictions apply:

• The YAML metadata block must occur at the beginning of the document (and there can be only one). If multiple files are given as arguments to pandoc, only the first can be a YAML metadata block.

• The leaf nodes of the YAML structure are parsed in isolation from each other and from the rest of the document. So, for example, you can’t use a reference link in these contexts if the link definition is somewhere else in the document.

According to my tests, there is at least one case in which two of those restrictions do not apply: with a markdown input, there can be any number of YAML metadata blocks and they can be anywhere in the document.

It might be worthwhile clarifying this in the User's Guide.

[jgm]

"In these formats" is meant to apply just to the commonmark-based formats (commonmark, gfm, commonmark_x).
Neither of the bullet points is true for markdown.
So we need to reword this slightly.

[jgm]

Made the change.