fix word errors in downloads.md (#5083)

Signed-off-by: Guangming Wang <guangming.wang@daocloud.io>

docs/downloads.md

@@ -16,9 +16,9 @@ NOTE: When `download_run_once` is true and `download_localhost` is false, all do
 
 On caching:
 
-* When `download_run_once` is `True`, all downloaded files will be cached locally in `download_cache_dir`, which defaults to `/tmp/kubespray_cache`. On subsequent provisioning runs, this local cache will be used to provision the nodes, minimizing bandwidth usage and improving provisining time. Expect about 800MB of disk space to be used on the ansible node for the cache. Disk space required for the image cache on the kubernetes nodes is a much as is needed for the largest image, which is currently slightly less than 150MB.
-* By default, if `download_run_once` is false, kubespray will not retreive the downloaded images and files from the remote node to the local cache, or use that cache to pre-provision those nodes. To force the use of the cache, set `download_force_cache` to `True`.
-* By default, cached images that are used to pre-provision the remote nodes will be deleted from the remote nodes after use, to save disk space. Setting download_keep_remote_cache will prevent the files from being deleted. This can be useful while developping kubespray, as it can decrease provisioning times. As a consequence, the required storage for images on the remote nodes will increase from 150MB to about 550MB, which is currently the combined size of all required container images.
+* When `download_run_once` is `True`, all downloaded files will be cached locally in `download_cache_dir`, which defaults to `/tmp/kubespray_cache`. On subsequent provisioning runs, this local cache will be used to provision the nodes, minimizing bandwidth usage and improving provisioning time. Expect about 800MB of disk space to be used on the ansible node for the cache. Disk space required for the image cache on the kubernetes nodes is a much as is needed for the largest image, which is currently slightly less than 150MB.
+* By default, if `download_run_once` is false, kubespray will not retrieve the downloaded images and files from the remote node to the local cache, or use that cache to pre-provision those nodes. To force the use of the cache, set `download_force_cache` to `True`.
+* By default, cached images that are used to pre-provision the remote nodes will be deleted from the remote nodes after use, to save disk space. Setting download_keep_remote_cache will prevent the files from being deleted. This can be useful while developing kubespray, as it can decrease provisioning times. As a consequence, the required storage for images on the remote nodes will increase from 150MB to about 550MB, which is currently the combined size of all required container images.
 
 Container images and binary files are described by the vars like ``foo_version``,
 ``foo_download_url``, ``foo_checksum`` for binaries and ``foo_image_repo``,