Improve page-meta-links page

This PR fixes a warning in the page-meta-links.html page where `.Path`
is a function to be removed soon. Warning message:

```
WARN 2022/06/17 21:20:35 .Path when the page is backed by a file is deprecated and will be removed in a future release. We plan to use Path for a canonical source path and you probably want to check the source is a file.
```

Author: tengqm

layouts/partials/page-meta-links.html

@@ -1,6 +1,7 @@
 {{/* template adapted from Docsy theme */}}
-{{ if .Path }}
-  {{ $pathFormatted := replace .Path "\\" "/" }}
+
+{{ if .File.Path }}
+  {{ $pathFormatted := replace .File.Path "\\" "/" }}
   {{ $gh_repo := ($.Param "github_repo") }}
   {{ $gh_subdir := ($.Param "github_subdir") }}
   {{ $gh_project_repo := ($.Param "github_project_repo") }}