Update 1.6 to 1.7 and 1.7-nighly to 1.8-nightly

Author: malfet

_includes/quick_start_local.html

@@ -1,5 +1,5 @@
 <p>Select your preferences and run the install command. Stable represents the most currently tested and supported version of PyTorch. This should
-   be suitable for many users. Preview is available if you want the latest, not fully tested and supported, 1.7 builds that are generated nightly.
+   be suitable for many users. Preview is available if you want the latest, not fully tested and supported, 1.8 builds that are generated nightly.
    Please ensure that you have <b>met the prerequisites below (e.g., numpy)</b>,  depending on your package manager. Anaconda is our recommended
    package manager since it installs all dependencies. You can also
   <a href="{{ site.baseurl }}/get-started/previous-versions">install previous versions of PyTorch</a>. Note that LibTorch is only available for C++.
@@ -33,7 +33,7 @@
         <div class="option-text">PyTorch Build</div>
       </div>
       <div class="col-md-6 option block version selected" id="stable">
-        <div class="option-text">Stable (1.6.0)</div>
+        <div class="option-text">Stable (1.7.0)</div>
       </div>
       <div class="col-md-6 option block version" id="preview">
         <div class="option-text">Preview (Nightly)</div>