doc: fix multiple doc typos

Use "file system" instead of "filesystem" throughout the document and
some other minor fixes.

PR-URL: https://github.com/libuv/libuv/pull/1278
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>

docs/src/fs.rst

@@ -9,7 +9,7 @@ operations. All functions defined in this document take a callback, which is
 allowed to be NULL. If the callback is NULL the request is completed synchronously,
 otherwise it will be performed asynchronously.
 
-All file operations are run on the threadpool, see :ref:`threadpool` for information
+All file operations are run on the threadpool. See :ref:`threadpool` for information
 on the threadpool size.
 
 
@@ -291,7 +291,7 @@ API
     Equivalent to :man:`realpath(3)` on Unix. Windows uses `GetFinalPathNameByHandle <https://msdn.microsoft.com/en-us/library/windows/desktop/aa364962(v=vs.85).aspx>`_.
 
     .. warning::
-        This function has certain platform specific caveats that were discovered when used in Node.
+        This function has certain platform-specific caveats that were discovered when used in Node.
 
         * macOS and other BSDs: this function will fail with UV_ELOOP if more than 32 symlinks are
           found while resolving the given path.  This limit is hardcoded and cannot be sidestepped.

docs/src/fs_event.rst

@@ -74,7 +74,7 @@ Data types
             UV_FS_EVENT_STAT = 2,
             /*
             * By default, event watcher, when watching directory, is not registering
-            * (is ignoring) changes in it's subdirectories.
+            * (is ignoring) changes in its subdirectories.
             * This flag will override this behaviour on platforms that support it.
             */
             UV_FS_EVENT_RECURSIVE = 4