Fix capitalization

Signed-off-by: YuPengZTE <yu.peng36@zte.com.cn>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

man/docker-run.1.md

@@ -992,7 +992,7 @@ network namespace, run this command:
 
 Note:
 
-Not all sysctls are namespaced. docker does not support changing sysctls
+Not all sysctls are namespaced. Docker does not support changing sysctls
 inside of a container that also modify the host system. As the kernel 
 evolves we expect to see more sysctls become namespaced.