Double quotes in alt text breaks the included graphic

[jennybc]

The solution appears to be using single quotes instead. Used with success here:

r-lib/gmailr@5e7b92a

Here's one example of several in readxl's vignettes:

Coming from this:

readxl/vignettes/cell-and-column-types.Rmd

Lines 148 to 152 in e090951

	#| fig-alt: Screenshot of the worksheet named "logical_coercion" inside the
	#| "type-me.xlsx" example spreadsheet. The cells in the first column
	#| (column A) have very mixed contents, such as empty, datetime, or string.
	#| The cells in the second column (column B) describe the contents of the
	#| first column in precise language.