DOC: assorted typo fixes in the documentation
this is 10th iteration of typo fixes
diff --git a/doc/internals/htx-api.txt b/doc/internals/htx-api.txt
index 77bbec9..e783e0e 100644
--- a/doc/internals/htx-api.txt
+++ b/doc/internals/htx-api.txt
@@ -147,7 +147,7 @@
free space free space
-Finally, when the usable free space is not enough to store a new block, unsuable
+Finally, when the usable free space is not enough to store a new block, unusable
parts may be get back with a full defragmentation. The payloads part is then
realigned at the beginning of the blocks array and the free space becomes
continuous again.