Pin the docs site config, and give it a favicon

docs/_config.yml

@@ -1 +1,27 @@
-theme: jekyll-theme-cayman
+# Jekyll config for the published docs site (https://dapperlib.dev).
+# Pinned here rather than left to GitHub's defaults, which take the site title and
+# description from the repo's name and description fields.
+
+title: Dapper
+description: A simple object mapper for .NET
+url: https://dapperlib.dev
+
+theme: jekyll-theme-cayman
+
+# Cayman renders "Download .zip/.tar.gz" buttons in its header when this is on, and
+# GitHub's default config turns it on; these ship as NuGet packages, not tarballs.
+show_downloads: false
+
+# Cayman renders the page title in its header banner, and the title comes from each page's
+# first heading - so without this the heading reads twice, banner then body.
+titles_from_headings:
+  strip_title: true
+
+# Not in the always-on GitHub Pages plugin set, so it has to be asked for; generates
+# sitemap.xml and robots.txt.
+plugins:
+  - jekyll-sitemap
+
+# Present only so the docs show up in the solution; not site content.
+exclude:
+  - docs.csproj

docs/_includes/head-custom.html

@@ -0,0 +1,3 @@
+<!-- Overrides the theme's own head-custom.html, which ships with the favicon line commented out. -->
+<link rel="icon" href="/assets/icon.png" type="image/png" sizes="256x256">
+<link rel="icon" href="/favicon.ico" sizes="16x16 32x32 48x48">