Use default branch name for URL instead of HEAD

Signed-off-by: Sora Morimoto <sora@morimoto.io>

Author: smorimoto

_data/stage3.json

@@ -130,7 +130,7 @@
       {
         "month": 5,
         "year": 2021,
-        "url": "https://github.com/tc39/notes/blob/HEAD/meetings/2021-05/may-25.md#resizable-arraybuffers-for-stage-3"
+        "url": "https://github.com/tc39/notes/blob/main/meetings/2021-05/may-25.md#resizable-arraybuffers-for-stage-3"
       }
     ]
   },
@@ -147,7 +147,7 @@
       {
         "month": 7,
         "year": 2021,
-        "url": "https://github.com/tc39/notes/blob/HEAD/meetings/2021-07/july-14.md#array-find-from-last"
+        "url": "https://github.com/tc39/notes/blob/main/meetings/2021-07/july-14.md#array-find-from-last"
       }
     ]
   },
@@ -164,7 +164,7 @@
       {
         "month": 8,
         "year": 2021,
-        "url": "https://github.com/tc39/notes/blob/HEAD/meetings/2021-08/aug-31.md#realms-renaming-bikeshedding-thread"
+        "url": "https://github.com/tc39/notes/blob/main/meetings/2021-08/aug-31.md#realms-renaming-bikeshedding-thread"
       }
     ]
   },

_layouts/menu.html

@@ -16,15 +16,15 @@
       <li class="submenu-item">
         <a
           class="menu-link"
-          href="https://github.com/tc39/agendas/blob/HEAD/2023/09.md"
+          href="https://github.com/tc39/agendas/blob/main/2023/09.md"
         >
           {{ site["navigation"]["TC39"]["agenda"] }}
         </a>
       </li>
       <li class="submenu-item">
         <a
           class="menu-link"
-          href="https://github.com/tc39/notes/tree/HEAD/meetings/2023-07"
+          href="https://github.com/tc39/notes/tree/main/meetings/2023-07"
         >
           {{ site["navigation"]["TC39"]["notes"] }}
         </a>

_layouts/page_footer.html

@@ -128,37 +128,37 @@ <h3 id="proposals-label">{{ site["footer"]["proposals"] }}</h3>
         <ul aria-labelledby="proposals-label">
           <li>
             <a
-              href="https://github.com/tc39/proposals/blob/HEAD/stage-0-proposals.md#stage-0-proposals"
+              href="https://github.com/tc39/proposals/blob/main/stage-0-proposals.md#stage-0-proposals"
               >Stage 0</a
             >
           </li>
           <li>
             <a
-              href="https://github.com/tc39/proposals/blob/HEAD/stage-1-proposals.md#stage-1-proposals"
+              href="https://github.com/tc39/proposals/blob/main/stage-1-proposals.md#stage-1-proposals"
               >Stage 1</a
             >
           </li>
           <li>
             <a
-              href="https://github.com/tc39/proposals/blob/HEAD/README.md#stage-2"
+              href="https://github.com/tc39/proposals/blob/main/README.md#stage-2"
               >Stage 2</a
             >
           </li>
           <li>
             <a
-              href="https://github.com/tc39/proposals/blob/HEAD/README.md#stage-27"
+              href="https://github.com/tc39/proposals/blob/main/README.md#stage-27"
               >Stage 2.7</a
             >
           </li>
           <li>
             <a
-              href="https://github.com/tc39/proposals/blob/HEAD/README.md#stage-3"
+              href="https://github.com/tc39/proposals/blob/main/README.md#stage-3"
               >Stage 3</a
             >
           </li>
           <li>
             <a
-              href="https://github.com/tc39/proposals/blob/HEAD/finished-proposals.md#finished-proposals"
+              href="https://github.com/tc39/proposals/blob/main/finished-proposals.md#finished-proposals"
               >Stage 4</a
             >
           </li>