Add scrollable menu and move github button (#935)

## Issue

#844 
#826 

## Change

- Move Github button and align in confval title
- Add separate scroll for menu and make it sticky

Author: cregourd

Makefile

@@ -1,5 +1,5 @@
 ## Global PHP arguments, applied to both docker and local execution
-PHP_ARGS ?= -d memory_limit=1024M
+PHP_ARGS ?= -d memory_limit=1024M -d date.timezone=UTC
 
 ## Docker wrapper, for raw php commands (so it's not required on the host)
 ## This container has no runtime for the `guides` project!

packages/typo3-docs-theme/assets/sass/layout/_structure.scss

@@ -62,6 +62,12 @@
 }
 .page-main-navigation {
     flex-grow: 0;
+    background-color: #fff;
+    z-index: 1;
+    position: sticky;
+    top: 114px;
+    height: auto;
+    overflow: auto;
     margin-left: calc(#{$grid-gutter-width} / 2 * -1);
     margin-right: calc(#{$grid-gutter-width} / 2 * -1);
     padding: calc(#{$grid-gutter-width} / 2);
@@ -71,6 +77,7 @@
         flex-shrink: 0;
         width: 15rem;
         margin: 0;
+        height: calc(100vh - 114px);
         margin-right: $grid-gutter-width;
         padding-right: calc(#{$grid-gutter-width} / 2);
         border-bottom: none;