;doc: add page TOCs to more dev docs

BENCHMARKS.md

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 # Benchmarks
 
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 Benchmarks are standard performance measurements,
 which we define using `bench` declarations in cabal files.
 There is [one in hledger.cabal](https://github.com/simonmichael/hledger/blob/master/hledger/hledger.cabal#L228),

CODE.md

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 # Code
 
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+</div>
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 hledger is a suite of applications, tools and libraries.
 The main hledger code repository is [github.com/simonmichael/hledger](https://github.com/simonmichael/hledger)
 (shortcut url `code.hledger.org`).

DOCS.md

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 # Docs
 
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 20191209: needs update. See also doc/README.
 
 ## Four kinds of documentation

FUNDING.md

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 # Funding
 
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 My vision for the hledger project has always been for it to be "accountable" and "self-sustaining", possibly through new forms of incentivisation. 
 Classic non-monetary FOSS communities are a beautiful and precious thing.
 Adding money can change their dynamic.

PULLREQUESTS.md

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 # Pull requests
 
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 Most contributed hledger code (and some of the project maintainer's code)
 is submitted and reviewed via Github pull requests.
 Here are some tips for contributing PRs to hledger.

TESTS.md

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 # Tests
 
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 About testing in the hledger project, as of 201809.
 
 ## Kinds of tests