docs: Add PROJECT_LOGO for documentation

docs/doxygen/logo-vector-clean.svg

@@ -0,0 +1 @@
+<svg enable-background="new 0 0 283.5 283.5" height="793.7" viewBox="0 0 793.7 793.7" width="793.7" xmlns="http://www.w3.org/2000/svg"><g stroke-width=".10005" transform="matrix(13.831 0 0 13.831 -1173.2 -291.34)"><path d="m94.968 35.193v-10.71l9.2751 5.355z" fill="#f7ae1a"/><path d="m94.968 35.193 9.2751-5.355v10.71z" fill="#e45e25"/><path d="m94.968 42.414 9.2751 5.355-9.2751 5.355z" fill="#d2343e"/><path d="m94.968 53.124 9.2751-5.355v10.71z" fill="#bb2033"/><path d="m94.968 53.124 9.2751 5.355-9.2751 5.355z" fill="#ab2333"/></g><g fill="#2e3436" fill-opacity=".19964" transform="matrix(13.831 0 0 13.831 -1361.02498 -319.002)"><path d="m57.472 29.867h-55.452l27.726-48.023z" stroke-width=".518" transform="matrix(-.16726 .09657 -.09657 -.16726 121.04 71.121)"/><path d="m148.27 69.213h-10.71l5.355-9.2751z" stroke-width=".10005" transform="matrix(-.86603 .5 .5 .86603 211.62 -57.046)"/><path d="m142.92-59.938h-10.71l5.355-9.2751z" stroke-width=".10005" transform="matrix(-.8660254 .5 -.5 -.8660254 211.614597 -57.0459)"/><path d="m57.472 29.867h-55.452l27.726-48.023z" stroke-width=".518" transform="matrix(0 .19314 -.19314 0 132.86 60.576)"/><path d="m57.472 29.867h-55.452l27.726-48.023z" stroke-width=".518" transform="matrix(.16726 .09657 -.09657 .16726 129.64 55.775)"/><path d="m57.472 29.867h-55.452l27.726-48.023z" transform="matrix(0 .19314 -.19314 0 142.13 55.221)"/></g><g transform="matrix(13.831 0 0 13.831 -1173.2 -291.34)"><g stroke-width=".10005"><path d="m94.968 63.834 9.2751-5.355v10.71z" fill="#7b2f44"/><path d="m104.24 69.189 9.2751-5.355-9.2751-5.355z" fill="#21376d"/><path d="m104.24 58.479 9.2751-5.355v10.71z" fill="#005082"/><path d="m113.52 63.834v-10.71l9.2751 5.355z" fill="#023e49"/><path d="m122.79 58.479-9.2751-5.355 9.2751-5.355z" fill="#007e96"/></g><path d="m122.79 58.479v-10.71l9.2751 5.355z" fill="#0a9197"/></g><g fill="#ccc" transform="translate(2.808 194.51)"><polygon/><polygon/></g></svg>

doxygen.cfg.in

@@ -51,7 +51,7 @@ PROJECT_BRIEF          = "API Documentation"
 # pixels and the maximum width should not exceed 200 pixels. Doxygen will copy
 # the logo to the output directory.
 
-PROJECT_LOGO           =
+PROJECT_LOGO           = docs/doxygen/logo-vector-clean.svg
 
 # The OUTPUT_DIRECTORY tag is used to specify the (relative or absolute) path
 # into which the generated documentation will be written. If a relative path is