Aligned to guideline and path optimized Android,

All were aligned accordingly and optimized to the following percentages:

Android - 31%
Bitbucket + 3%

Updated README with the new file sizes.

images/svg/android.svg

@@ -1 +1 @@
-<svg xmlns="http://www.w3.org/2000/svg" fill="#a4c639" aria-label="Android" role="img" viewBox="0 0 512 512"><rect width="512" height="512" fill="#fff" rx="15%"/><path d="M87 174c-16 0-29 13-29 29v121c0 16 13 29 29 29s29-13 29-29V203c0-16-13-29-29-29zm339 0c-17 0-30 13-30 29v121c0 16 13 29 30 29 16 0 29-13 29-29V203c0-16-13-29-29-29zM208 312c-16 0-29 13-29 29v121c0 16 13 29 29 29s29-13 29-29V341c0-16-13-29-29-29zm97 0c-17 0-30 13-30 29v121c0 16 13 29 30 29 16 0 29-13 29-29V341c0-16-13-29-29-29z"/><path d="M176 21l-2 1c-2 1-3 3-2 5l21 37c-40 21-66 60-66 104h259c0-44-27-83-66-104l20-37c1-2 1-4-1-5l-2-1-4 2-21 38a138 138 0 0 0-112 0l-21-38-3-2zm-49 158v187c0 18 14 32 31 32h196c18 0 32-14 32-32V179z"/><circle cx="196.5" cy="110" r="11" fill="#fff"/><circle cx="316.5" cy="110" r="11" fill="#fff"/></svg>
+<svg fill="#a4c639" stroke-linecap="round" viewBox="0 0 512 512" xmlns="http://www.w3.org/2000/svg" aria-label="Android" role="img"><rect fill="#fff" height="512" rx="50%" width="512"/><g stroke="#a4c639"><path d="m107 212v106m299-106v106m-107 66v56m-85-56v56" stroke-width="58"/><path d="m203 88-17-32m123 32 18-32" stroke-width="8"/></g><path d="m257 76c-76 0-115 60-115 105h229c0-47-42-104-114-105zm-115 115v164c0 16 13 29 28 29h172c16 0 29-13 29-29v-164z"/><circle cx="204" cy="130" fill="#fff" r="9"/><circle cx="309" cy="130" fill="#fff" r="9"/></svg>