Fix a few typos in the vendored_dirs stanza documentation

Signed-off-by: Nathan Rebours <nathan.p.rebours@gmail.com>

doc/dune-files.rst

@@ -884,10 +884,10 @@ instead of this stanza. For example:
 vendored_dirs (since 1.11)
 -------------------------
 
-Dune supports vendoring of other dune based natively since simply copying a
-project into a subdirectory of your own project will work. Simply doing that has
-a few limitation though. You can workaround those by explicitly marking such
-directories as containing vendored code.
+Dune supports vendoring of other dune-based projects natively since simply
+copying a project into a subdirectory of your own project will work. Simply
+doing that has a few limitations though. You can workaround those by explicitly
+marking such directories as containing vendored code.
 
 Example:
 
@@ -900,7 +900,7 @@ Dune will not resolve aliases in vendored directories meaning by default it will
 not build all installable targets, run the test, format or lint the code located
 in such a directory while still building the parts your project depend upon.
 Libraries and executable in vendored directories will also be built with a ``-w
--a`` flag to suppress all warnings and prevent polution of your build output.
+-a`` flag to suppress all warnings and prevent pollution of your build output.
 
 
 .. _include_subdirs: