doc: show logo only

Since logo already brings to home page, remove the link displayed above.
It saves some vertical pixels while making docs nicer. Also adjusted
wy-menu-vertical max-height to account for the new height (note: was
wrong before).

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
diff --git a/doc/_static/css/custom.css b/doc/_static/css/custom.css
index ca1c290..9d2b5c9 100644
--- a/doc/_static/css/custom.css
+++ b/doc/_static/css/custom.css
@@ -837,7 +837,7 @@
 .wy-menu.wy-menu-vertical {
     overflow-y: auto;
     overflow-x: hidden;
-    max-height: calc(100% - 348px);
+    max-height: calc(100% - 243px);
 }
 @media screen and (max-width: 768px) {
     .wy-nav-side {
diff --git a/doc/conf.py b/doc/conf.py
index c41d3fe..c04e880 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -116,7 +116,10 @@
 
 html_theme = "sphinx_rtd_theme"
 html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
-html_theme_options = {"prev_next_buttons_location": None}
+html_theme_options = {
+    "logo_only": True,
+    "prev_next_buttons_location": None
+}
 html_title = "Zephyr Project Documentation"
 html_logo = "_static/images/logo.svg"
 html_favicon = "images/zp_favicon.png"
@@ -134,7 +137,6 @@
     "show_license": True,
     "docs_title": docs_title,
     "is_release": is_release,
-    "theme_logo_only": False,
     "current_version": version,
     "versions": (
         ("latest", "/"),