v2Documentation fix related to hash algorithm

I was doing some research on the SHA256 implementation, and I discovered a mismatch between the docs and the code. I have a patch attached that fixes the docs.

This is version 2, which has a slightly nicer commit message as suggested by Martin Ågren.

Martin Ågren also mentioned[0] this discrepancy is added on 2020-02-22 in 3c9331a129, which added both the documentation and the implementation. As developers-only as this variable is, that commit was not in v2.26.0, so this might be worth fixing before cutting v2.27.0.

[0] https://lore.kernel.org/git/20200525144138.1624272-1-toon@iotcl.com/T/#m637dc0692962e882928e035888435267b784ee17

Toon Claes (1):
  Documentation: correct hash environment variable

 Documentation/git.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 2.27.0.rc1.73.g31835d1b01

To set the default hash algorithm you can set the `GIT_DEFAULT_HASH` environment variable. In the documentation this variable is named `GIT_DEFAULT_HASH_ALGORITHM`, which is incorrect.

Signed-off-by: Toon Claes <toon@iotcl.com>
---
 Documentation/git.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Toon Claes <toon@iotcl.com> writes:

My reading stuttered while reading words around "to set ... you can set"; I would have written

	The GIT_DEFAULT_HASH environment variable, which is the way
	to specify the default hash algorithm, was misspelled in the
	documentation.  Fix it.

but it's OK.

As you said, bc/sha-256-part-1-of-4 is new in this release, so let's merge this fix down before the final.

Thanks.