Update git-clone task and document changes in behaviour

Earlier git-clone assumes `master` as default branch, but after #2835
`master` is no more default branch. Hence, updated the git clone task
fetch a remote repository's default branch instead of assuming "master"
when revision is "".

Signed-off-by: Divyansh42 <diagrawa@redhat.com>

task/git-clone/0.1/README.md

@@ -53,4 +53,3 @@ The following pipelines demonstrate usage of the git-clone Task:
 - [Cloning a branch](../0.1/samples/git-clone-checking-out-a-branch.yaml)
 - [Checking out a specific git commit](../0.1/samples/git-clone-checking-out-a-commit.yaml)
 - [Checking out a git tag and using the "commit" Task Result](../0.1/samples/using-git-clone-result.yaml)
-

task/git-clone/0.1/git-clone.yaml

@@ -116,4 +116,4 @@ spec:
           exit $EXIT_CODE
         fi
         # Make sure we don't add a trailing newline to the result!
-        echo -n "$RESULT_SHA" > $(results.commit.path)
+        echo -n "$RESULT_SHA" > $(results.commit.path)

task/git-clone/0.2/README.md

@@ -1,10 +1,6 @@
-# Git Task
+# `git-clone`
 
-This `Task` is Git task to work with repositories used by other tasks
-in your Pipeline.
-## `git-clone`
-
-**Please Note: this Task is only compatible with Tekton Pipelines versions 0.11-rc1 and greater!**
+**Please Note: this Task is only compatible with Tekton Pipelines versions 0.14.0 and greater!**
 
 This `Task` has two required inputs:
 
@@ -32,8 +28,8 @@ as well as
 ### Parameters
 
 * **url**: git url to clone (_required_)
-* **revision**: git revision to checkout (branch, tag, sha, ref…) (_default_: master)
-* **refspec**: git refspec to fetch before checking out revision (_default_:refs/heads/master:refs/heads/master)
+* **revision**: git revision to checkout (branch, tag, sha, ref…) (_default_: "")
+* **refspec**: git refspec to fetch before checking out revision (_default_:"")
 * **submodules**: defines if the resource should initialize and fetch the submodules (_default_: true)
 * **depth**: performs a shallow clone where only the most recent commit(s) will be fetched (_default_: 1)
 * **sslVerify**: defines if http.sslVerify should be set to true or false in the global git config (_default_: true)
@@ -51,11 +47,12 @@ as well as
 
 ## Usage
 
-### `git-clone`
+If the `revision` is not provided in the param of the taskrun
+then it will auto-detect the branch as specified by the `default`
+in the respective git repository.
 
 The following pipelines demonstrate usage of the git-clone Task:
 
-- [Cloning a branch](../0.1/samples/git-clone-checking-out-a-branch.yaml)
-- [Checking out a specific git commit](../0.1/samples/git-clone-checking-out-a-commit.yaml)
-- [Checking out a git tag and using the "commit" Task Result](../0.1/samples/using-git-clone-result.yaml)
-
+- [Cloning a branch](../0.2/samples/git-clone-checking-out-a-branch.yaml)
+- [Checking out a specific git commit](../0.2/samples/git-clone-checking-out-a-commit.yaml)
+- [Checking out a git tag and using the "commit" Task Result](../0.2/samples/using-git-clone-result.yaml)

task/git-clone/0.2/git-clone.yaml

@@ -28,7 +28,7 @@ spec:
     - name: revision
       description: git revision to checkout (branch, tag, sha, ref…)
       type: string
-      default: master
+      default: ""
     - name: refspec
       description: (optional) git refspec to fetch before checking out revision
       default: ""