doc FEATURE building process description

High level information providing information about different build
types, their purpose and available cmake options a make targets.
diff --git a/Doxyfile.in b/Doxyfile.in
index 9abc3c9..848c353 100644
--- a/Doxyfile.in
+++ b/Doxyfile.in
@@ -781,7 +781,7 @@
 # spaces. See also FILE_PATTERNS and EXTENSION_MAPPING
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-INPUT                  = doc/transition.dox @DOXY_HEADERS@
+INPUT                  = doc/build.dox doc/transition.dox @DOXY_HEADERS@
 
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 # that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses