* Update install instructions for Bash and Zsh

* Synchronize README.md with `pyenv init`
* Add a ~/.bash_profile note
* Concatenate shims activation into installation for brevity
  (Pyenv can't be used meaningfully without shims anyway)
  Otherwise, we'd need to duplicate all the ~/.profile shenanigans in both sections
* Update based on feedback
* Proofread

Add a hint for cases when ~/.profile sources ~/.rc

Our ~/.rc logic must run after the ~/.profile one

Place full shell configuration instructions into `pyenv init`

including initial PATH and PYENV_ROOT entries.
The migration hint proved to be unclear to users without them.

In certain cases, a user wants to know the cached filename to add the file themselves,
see https://github.com/pyenv/pyenv/issues/1743 .
Since we report both a filename and a URL anyway, there's no reason to report a wrong one.

Update generated configuration files before run ./configure

This behavior is only triggered when the version is provided as an empty string,
is undocumented and breaks if multiple local versions are specified
(rightly so since it's unclear which of them to install).

Only test the permission bit that we're setting

Split startup logic into PATH and everything else

E.g. for a GUI session, ~/.profile is executed by the GUI login "shell" at its startup
so one needs to fully log out and log back in.
Before that, the change would only be seen by shells explicitly started as login shells.

Bump OpenSSL to 1.1.1x for all Pythons that support MacOS 11

To support building for Apple ARM64 which was introduced in MacOS 11
OpenSSL added support for Apple ARM in 1.1.1
(61168b5b8d).
Python added support for MacOS 11 in 3.7.8+, 3.8.4+, 3.9.0+
(https://github.com/python/cpython/pull/21113 and backports).

To facilitate migration

PATH manipulation should be done in ~/.profile rather than ~/.*rc since .rc can be sourced multiple times

With functions, we have more leeway in what to call

Co-authored-by: Josh Friend <josh@fueledbycaffeine.com>

Co-authored-by: Josh Friend <josh@fueledbycaffeine.com>

Add CPython 3.10.0b1

Add GraalPython 21.1.0

Add CPython 3.10.0a7

docs(README): fix info about version-file separator

Any whitespace doesn't work, need version per line.

List versions starting with a dot

feat: support (skip) commented lines in version-file

pypy3.7-7.3.4

Sometimes it is convenient to be able to temporarily disable something
in a version-file. Because these files often aren't necessarily tracked
in a SCM, especially when working with virtualenvs, the SCM diffs won't
help with showing removed lines which are currently the only way to
disable something.