docs: remove duplicated table of contents (#557)

* docs: remove duplicated table of contents

Signed-off-by: Asra Ali <asraa@google.com>

* fix action installation list

Signed-off-by: Asra Ali <asraa@google.com>

---------

Signed-off-by: Asra Ali <asraa@google.com>

README.md

@@ -20,7 +20,7 @@
   - [Compilation from source](#compilation-from-source)
     - [Option 1: Install via go](#option-1-install-via-go)
     - [Option 2: Compile manually](#option-2-compile-manually)
-    - [Option 3: Use the installer Action](#option-3-use-the-installer-action)
+  - [Use the installer Action on GitHub](#use-the-installer-action-on-github-actions)
   - [Download the binary](#download-the-binary)
 - [Available options](#available-options)
 - [Option list](#option-list)
@@ -81,38 +81,6 @@ It currently supports verifying provenance generated by:
 1. [SLSA generator](https://github.com/slsa-framework/slsa-github-generator)
 1. [Google Cloud Build (GCB)](https://cloud.google.com/build/docs/securing-builds/view-build-provenance).
 
----
-
-[Installation](#installation)
-
-- [Compilation from source](#compilation-from-source)
-- [Download the binary](#download-the-binary)
-
-[Available options](#available-options)
-
-- [Option list](#option-list)
-- [Option details](#option-details)
-
-[Verification for GitHub builders](#verification-for-github-builders)
-
-- [Artifacts](#artifacts)
-- [Containers](#containers)
-
-[Verification for Google Cloud Build](#verification-for-google-cloud-build)
-
-- [Artifacts](#artifacts-1)
-- [Containers](#containers-1)
-
-[Known Issues](#known-issues)
-
-[Technical design](#technial-design)
-
-- [Blog posts](#blog-posts)
-- [Specifications](#specifications)
-- [TOCTOU attacks](#toctou-attacks)
-
----
-
 ## Installation
 
 You have two options to install the verifier.
@@ -168,7 +136,7 @@ $ cd slsa-verifier && git checkout v2.1.0
 $ go run ./cli/slsa-verifier <options>
 ```
 
-#### Option 3: Use the installer Action
+### Use the installer Action on GitHub Actions
 
 If you need to install the verifier to run in a GitHub workflow, use the installer Action as described in [actions/installer/README.md](./actions/installer/README.md).