CHANGELOG: document git_filter_init and GIT_FILTER_INIT

CHANGELOG: document git_filter_init and GIT_FILTER_INIT

Merge pull request libgit2#4262 from libgit2/ethomson/bump-v26

Update version number to 0.26

Merge pull request libgit2#4076 from libgit2/cmn/sec-update-25

security updates for v0.25

Merge pull request libgit2#4075 from libgit2/cmn/sec-update-24

Security updates for v0.24

Merge pull request libgit2#3980 from tiennou/doc-fixes

Documentation fixes

Merge pull request libgit2#3980 from tiennou/doc-fixes

Documentation fixes

Bump version to 0.24.5

Merge pull request libgit2#4029 from libgit2/cmn/windows-no-concurren…

…t-compress

refdb: disable concurrent compress in the threading tests on Windows

Merge pull request libgit2#4007 from libgit2/cmn/bump-v25

Bump version number to v0.25