Typo fix in spgtextproc.c

diff --git a/src/backend/access/spgist/spgtextproc.c b/src/backend/access/spgist/spgtextproc.c
index e430d9c..f1379e0 100644
--- a/src/backend/access/spgist/spgtextproc.c
+++ b/src/backend/access/spgist/spgtextproc.c
@@ -23,7 +23,7 @@
 
 
 /*
- * In the worst case, a inner tuple in a text radix tree could have as many
+ * In the worst case, an inner tuple in a text radix tree could have as many
  * as 256 nodes (one for each possible byte value).  Each node can take 16
  * bytes on MAXALIGN=8 machines.  The inner tuple must fit on an index page
  * of size BLCKSZ.	Rather than assuming we know the exact amount of overhead