trurl: পুরোনো সংস্করণ ডাউনলোড করুন

What's Changed
- COPYING: add the "and many contributors" text from the curl license by @bagder in #374
- Update README.md to link to the getting trurl wiki page by @jacobmealey in #378
- Generate ZSH completions base on trurl.md by @jacobmealey in #379
- scripts: import cd2nroff from curl by @bagder in #384
- Makefile: only create MANDIR when manpage is installed by @sertonix in #381
- trurl: handle zero length query pairs by @bagder in #388
- move mkrelease and checksrc into scripts/ by @bagder in #385