Improve docs.

Author: kinyoklion

libs/client-sdk/Doxyfile

@@ -829,7 +829,7 @@ WARN_LOGFILE           =
 # spaces. See also FILE_PATTERNS and EXTENSION_MAPPING
 # Note: If this tag is empty the current directory is searched.
 
-INPUT                  = include src
+INPUT                  = include src docs ../common/include ../common/src
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses
@@ -1026,7 +1026,7 @@ FILTER_SOURCE_PATTERNS =
 # (index.html). This can be useful if you have a project on for instance GitHub
 # and want to reuse the introduction page also for the doxygen output.
 
-USE_MDFILE_AS_MAINPAGE = docs/mainpage.md
+USE_MDFILE_AS_MAINPAGE = ./docs/doc.md
 
 #---------------------------------------------------------------------------
 # Configuration options related to source browsing

libs/client-sdk/docs/doc.md

@@ -1 +1,9 @@
 # SDK Layout and Overview
+
+## Basic Functionality
+
+The following pages document the core of the API, every application will use these portions of the SDK:
+
+- [Client](@ref launchdarkly::client_side::Client)
+- [Config Builder](@ref launchdarkly::config::detail::builders::ConfigBuilder)
+- [Context Builder](@ref launchdarkly::ContextBuilder)