docs: Fix a few typos

[timgates42]

There are small typos in:

• README.md
• examples/bot_ping.py
• examples/bot_source_of_reply.py
• examples/bot_with_context.py
• pytg/init.py
• pytg/exceptions.py
• pytg/fix_msg_array.py
• pytg/sender.py

Fixes:

• Should read convenience rather than convinience.
• Should read careful rather than carefull.
• Should read because rather than becaues.
• Should read formatted rather than formated.
• Should read fails rather than failes.
• Should read succeed rather than suceed.
• Should read something rather than somethhing.
• Should read returned rather than returnded.
• Should read respectively rather than respectivly.
• Should read conversations rather than converations.
• Should read considered rather than concidered.
• Should read available rather than availabe.
• Should read affected rather than affacted.

Semi-automated pull request generated by
https://github.com/timgates42/meticulous/blob/master/docs/NOTE.md

[luckydonald]

It ain't "init.py" but "__init__.py".
Do your markdown escaping, sigh.

[luckydonald]

Also those fixes should be per file, that makes it much easier to understand and triage