document will_render better

diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index 77f336dca01ad966a09f8e9c461ab0df82100b48..0e1839c6ca31157ddf0b5edcfd4d78529fbb2327 100644 (file)
--- a/doc/plugins/write.mdwn
+++ b/doc/plugins/write.mdwn
@@ -449,6 +449,10 @@ destination directory), register that the page will result in that file
 being rendered. It's important to call this before writing to any file in
 the destination directory.
 
 being rendered. It's important to call this before writing to any file in
 the destination directory.
 

+Ikiwiki uses this information to automatically clean up rendered files when
+the page that rendered them goes away or is changes to no longer render
+them. will_render also does a few important security checks.
+

 #### `pagetype($)`
 
 Given the name of a source file, returns the type of page it is, if it's
 #### `pagetype($)`
 
 Given the name of a source file, returns the type of page it is, if it's