Update cheatsheets

tldr/bitcoind

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+---
+syntax: markdown
+tags: [tldr, common]
+source: https://github.com/tldr-pages/tldr.git
+---
+# bitcoind
+
+> Bitcoin Core daemon.
+> Uses the configuration defined in `bitcoin.conf`.
+> More information: <https://manned.org/bitcoind>.
+
+- Start the Bitcoin Core daemon (in the foreground):
+
+`bitcoind`
+
+- Start the Bitcoin Core daemon in the background (use `bitcoin-cli stop` to stop):
+
+`bitcoind -daemon`
+
+- Start the Bitcoin Core daemon on a specific network:
+
+`bitcoind -chain={{main|test|signet|regtest}}`
+
+- Start the Bitcoin Core daemon using specific config file and data directory:
+
+`bitcoind -conf={{path/to/bitcoin.conf}} -datadir={{path/to/directory}}`

tldr/qalc

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+---
+syntax: markdown
+tags: [tldr, common]
+source: https://github.com/tldr-pages/tldr.git
+---
+# qalc
+
+> Powerful and easy to use command-line calculator.
+> See also: `bc`.
+> More information: <https://qalculate.github.io/manual/qalc.html>.
+
+- Launch in [i]nteractive mode:
+
+`qalc {{--interactive}}`
+
+- Launch in [t]erse mode (print the results only):
+
+`qalc --terse`
+
+- Update currency [e]xchange rates:
+
+`qalc --exrates`
+
+- Perform calculations non-interactively:
+
+`qalc {{66+99|2^4|6 feet to cm|1 bitcoin to USD|20 kmph to mph|...}}`
+
+- List all supported functions/prefixes/units/variables:
+
+`qalc --{{list-functions|list-prefixes|list-units|list-variables}}`
+
+- Execute commands from a [f]ile:
+
+`qalc --file {{path/to/file}}`