7e39082eec Improve doc of `Script::push_verify` (Martin Habovštiak)
Pull request description:
This rewords the doc to have a reasonable summary, adds a little background explaining the opcode behavior and the effect of the function when called multiple times.
Closes#1154
ACKs for top commit:
tcharding:
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apoelstra:
ACK 7e39082eec
Tree-SHA512: 7f0142c9fcec8ef5b30779f1d22922219180aa103ce2f3039412b1d6b46aa7ee2522181e23a76f9ba5fd84720ef3ff3daa8233d71cf10008f5e3b805b5a5c470