Added links in the README to other libc implementations.
Added links in the README to other libc implementations.

ZakharBondia/libc11,ZakharBondia/libc11,dryc/libc11,dryc/libc11,dryproject/libc11,dryc/libc11,ZakharBondia/libc11,dryproject/libc11,dryproject/libc11