DOC: Fix typos in different subsections of the documentation

Fix typos found in the design-thoughts, internals and lua-api
subsections of the documentation.
diff --git a/doc/design-thoughts/entities-v2.txt b/doc/design-thoughts/entities-v2.txt
index 8c9eb48..905888e 100644
--- a/doc/design-thoughts/entities-v2.txt
+++ b/doc/design-thoughts/entities-v2.txt
@@ -61,7 +61,7 @@
   - if a data-layer accept() has been performed
     => possibly 2 bits, to indicate the need to free()
 
-On the connect() side, we need to konw :
+On the connect() side, we need to know :
   - the desire to send a header (eg: send-proxy)
   - if this header has been sent
     => maybe both info might be combined