readme: Update and modernize with markdown

Signed-off-by: David Goulet <dgoulet@torproject.org>

README

-[![pipeline status](https://gitlab.torproject.org/tpo/core/tor/badges/main/pipeline.svg)](https://gitlab.torproject.org/tpo/core/tor/-/commits/main)
-
-Tor protects your privacy on the internet by hiding the connection
-between your Internet address and the services you use. We believe Tor
-is reasonably secure, but please ensure you read the instructions and
-configure it properly.
-
-To build Tor from source:
-        ./configure && make && make install
-
-To build Tor from a just-cloned git repository:
-        sh autogen.sh && ./configure && make && make install
-
-Home page:
-        https://www.torproject.org/
-
-Download new versions:
-        https://www.torproject.org/download/download.html
-
-Documentation, including links to installation and setup instructions:
-        https://www.torproject.org/docs/documentation.html
-
-Making applications work with Tor:
-        https://gitlab.torproject.org/legacy/trac/-/wikis/doc/TorifyHOWTO
-
-Frequently Asked Questions:
-        https://www.torproject.org/docs/faq.html
-
-Release timeline:
-        https://gitlab.torproject.org/tpo/core/team/-/wikis/NetworkTeam/CoreTorReleases
-
-To get started working on Tor development:
-        See the doc/HACKING directory.

README.md

+Tor protects your privacy on the internet by hiding the connection between
+your Internet address and the services you use. We believe Tor is reasonably
+secure, but please ensure you read the instructions and configure it properly.
+
+## Build
+
+To build Tor from source:
+
+```
+./configure
+make
+make install
+```
+
+To build Tor from a just-cloned git repository:
+
+```
+./autogen.sh
+./configure
+make
+make install
+```
+
+## Releases
+
+The tarballs, checksums and signatures can be found: https://dist.torproject.org
+
+- Checksum: `<tarball-name>.sha256sum`
+- Signatures: `<tarball-name>.sha256sum.asc`
+
+### Schedule
+
+You can find our release schedule here:
+
+- https://gitlab.torproject.org/tpo/core/team/-/wikis/NetworkTeam/CoreTorReleases
+
+### Keys that CAN sign a release
+
+The following keys are the maintainers of this repository. One or many of
+these keys can sign the releases, do NOT expect them all:
+
+- Alexander Færøy:
+    [514102454D0A87DB0767A1EBBE6A0531C18A9179](https://keys.openpgp.org/vks/v1/by-fingerprint/1C1BC007A9F607AA8152C040BEA7B180B1491921)
+- David Goulet:
+    [B74417EDDF22AC9F9E90F49142E86A2A11F48D36](https://keys.openpgp.org/vks/v1/by-fingerprint/B74417EDDF22AC9F9E90F49142E86A2A11F48D36)
+- Nick Mathewson:
+    [2133BC600AB133E1D826D173FE43009C4607B1FB](https://keys.openpgp.org/vks/v1/by-fingerprint/2133BC600AB133E1D826D173FE43009C4607B1FB)
+
+## Development
+
+See our hacking documentation in [doc/HACKING/](./doc/HACKING).
+
+## Resources
+
+Home page:
+
+- https://www.torproject.org/
+
+Download new versions:
+
+- https://www.torproject.org/download/download.html
+
+Documentation, including links to installation and setup instructions:
+
+- https://www.torproject.org/docs/documentation.html
+
+Frequently Asked Questions:
+
+- https://www.torproject.org/docs/faq.html
+