Fix spelling and gramatical errors

Fixed 3 typos in design.rst
Signed-off-by: Xiaxi Shen <shenxiaxi26@gmail.com>
Link: https://lore.kernel.org/r/20240807070536.14536-1-shenxiaxi26@gmail.comReviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Documentation/filesystems/iomap/design.rst

@@ -142,9 +142,9 @@ Definitions
  * **pure overwrite**: A write operation that does not require any
    metadata or zeroing operations to perform during either submission
    or completion.
-   This implies that the fileystem must have already allocated space
+   This implies that the filesystem must have already allocated space
    on disk as ``IOMAP_MAPPED`` and the filesystem must not place any
-   constaints on IO alignment or size.
+   constraints on IO alignment or size.
    The only constraints on I/O alignment are device level (minimum I/O
    size and alignment, typically sector size).
 
@@ -394,7 +394,7 @@ iomap is concerned:
 
  * The **upper** level primitive is provided by the filesystem to
    coordinate access to different iomap operations.
-   The exact primitive is specifc to the filesystem and operation,
+   The exact primitive is specific to the filesystem and operation,
    but is often a VFS inode, pagecache invalidation, or folio lock.
    For example, a filesystem might take ``i_rwsem`` before calling
    ``iomap_file_buffered_write`` and ``iomap_file_unshare`` to prevent