fix grammar

1 files changed, 1 insertions, 1 deletions

diff --git a/_intro.qmd b/_intro.qmd
index 7c4c5a1..8f90855 100644
--- a/_intro.qmd
+++ b/_intro.qmd
@@ -96,7 +96,7 @@ that strips semantic text annotations from the Markdown content,
 so that further processing need not know about the new markup,
 as illustrated in @fig-phase1.
 
-![Filter strips annotations from content.](workflow/phase1.svg){#fig-phase1}
+![A filter strips annotations from content.](workflow/phase1.svg){#fig-phase1}
 
 ### Evolve accepted formats and tools