docs: update references to tool name and invocation

Signed-off-by: zhouhao <[email protected]>

Author: zhouhao

README.md

@@ -1,6 +1,6 @@
-# oci-image-tools [![Build Status](https://travis-ci.org/opencontainers/image-tools.svg?branch=master)](https://travis-ci.org/opencontainers/image-tools)
+# oci-image-tool [![Build Status](https://travis-ci.org/opencontainers/image-tools.svg?branch=master)](https://travis-ci.org/opencontainers/image-tools)
 
-`oci-image-tools` is a collection of tools for working with the [OCI image format specification](https://github.com/opencontainers/image-spec).
+`oci-image-tool` is a collection of tools for working with the [OCI image format specification](https://github.com/opencontainers/image-spec).
 
 ## Install
 

man/oci-image-tool-create.1.md

@@ -1,8 +1,8 @@
-% OCI(1) OCI-CREATE-RUNTIME-BUNDLE User Manuals
+% OCI(1) OCI-IMAGE-TOOL User Manuals
 % OCI Community
 % JULY 2016
 # NAME
-oci-image-tool-create \- Create an OCI runtime bundle
+oci-image-tool create \- Create an OCI runtime bundle
 
 # SYNOPSIS
 **oci-image-tool create** [src] [dest] [OPTIONS]

man/oci-image-tool-unpack.1.md

@@ -1,4 +1,4 @@
-% OCI(1) OCI-UNPACK User Manuals
+% OCI(1) OCI-IMAGE-TOOL User Manuals
 % OCI Community
 % JULY 2016
 # NAME

man/oci-image-tool-validate.1.md

@@ -1,4 +1,4 @@
-% OCI(1) OCI-IMAGE-VALIDATE User Manuals
+% OCI(1) OCI-IMAGE-TOOL User Manuals
 % OCI Community
 % JULY 2016
 # NAME