Gemini logo (#849)

* Added gemini.svg and reference files

* Optimised gemini.svg file (decimal precision: 2)

* Updated README.md

images/reference/gemini.svg

@@ -0,0 +1,12 @@
+<svg xmlns="http://www.w3.org/2000/svg"
+aria-label="Gemini" role="img"
+viewBox="0 0 512 512"><path 
+d="M0 0h512v512H0"
+fill="#fff"/>
+<path d="M434 256.86A189.08 189.08 0 0 0 256.86 434h-.72A189.06 189.06 0 0 0 79 256.86v-.72A189.06 189.06 0 0 0 256.14 79h.72A189.08 189.08 0 0 0 434 256.14v.72Z" fill="url(#a)"/>
+<radialGradient id="a" cx="0" cy="0" r="1" gradientTransform="matrix(357.94175 121.03963 -969.60352 2867.33838 114.23 223.28)" gradientUnits="userSpaceOnUse">
+<stop offset=".07" stop-color="#9168C0"/>
+<stop offset=".34" stop-color="#5684D1"/>
+<stop offset=".67" stop-color="#1BA1E3"/>
+</radialGradient>
+</svg>

images/reference/gemini.url

@@ -0,0 +1 @@
+https://gemini.google.com/