Modifies replace-tokens task according to the new reorg proposal

Changes include:
  - adds version label
  - adds a minimum pipeline versions supported by the task
  - adds display name for task
  - adds tags for task
  - modified description to add a summary

This patch also moves the replace-tokens files to the task directory

Issue: #386

Signed-off-by: Puneet Punamiya <ppunamiy@redhat.com>

task/replace-tokens/0.1/README.md

@@ -35,7 +35,7 @@ The above same can be done for the `YAML` file also.
 ## Install the Task
 
 ```
-kubectl apply -f https://raw.githubusercontent.com/tektoncd/catalog/master/replace-tokens/replace-tokens.yaml
+kubectl apply -f https://raw.githubusercontent.com/tektoncd/catalog/master/task/replace-tokens/0.1/replace-tokens.yaml
 ```
 
 ## Parameters

task/replace-tokens/0.1/replace-tokens.yaml

@@ -2,7 +2,18 @@ apiVersion: tekton.dev/v1beta1
 kind: Task
 metadata:
   name: replace-tokens
+  labels:
+    app.kubernetes.io/version: "0.1"
+  annotations:
+    tekton.dev/pipelines.minVersion: "0.12.1"
+    tekton.dev/tags: tokens
+    tekton.dev/displayName: "replace tokens"
 spec:
+  description: >-
+    This task can be used to replace tokens in a file.
+
+    The supported file types are YAML and JSON.
+
   workspaces:
     - name: source
     - name: token