libgit2: Update documentation

Signed-off-by: Paulo Gomes <paulo.gomes@weave.works>

DEVELOPMENT.md

@@ -13,27 +13,6 @@ There are a number of dependencies required to be able to run the controller and
 - [Install Docker](https://docs.docker.com/engine/install/)
 - (Optional) [Install Kubebuilder](https://book.kubebuilder.io/quick-start.html#installation)
 
-The [libgit2](https://libgit2.org/) dependency is now automatically managed by the Makefile logic.
-However, it depends on [pkg-config](https://freedesktop.org/wiki/Software/pkg-config/) being installed:
-
-### macOS
-
-```console
-$ # Ensure pkg-config is installed
-$ brew install pkg-config
-```
-
-### Linux
-
-```console
-$ # Ensure pkg-config is installed
-$ pacman -S pkgconf
-```
-
-**Note:** Example shown is for Arch Linux, but likewise procedure can be
-followed using any other package manager. Some distributions may have slight 
-variation of package names (e.g. `apt install -y pkg-config`).
-
 In addition to the above, the following dependencies are also used by some of the `make` targets:
 
 - `controller-gen` (v0.7.0)
@@ -149,18 +128,11 @@ Create a `.vscode/launch.json` file:
             "type": "go",
             "request": "launch",
             "mode": "auto",
-            "envFile": "${workspaceFolder}/build/.env",
             "program": "${workspaceFolder}/main.go"
         }
     ]
 }
 ```
 
-Create the environment file containing details on how to load 
-`libgit2` dependencies:
-```bash
-make env
-```
-
 Start debugging by either clicking `Run` > `Start Debugging` or using
 the relevant shortcut.

docs/spec/v1beta2/gitrepositories.md

@@ -228,8 +228,7 @@ spec:
     branch: <branch-name>
 ```
 
-Using the [`go-git` Git implementation](#git-implementation), this will perform
+This will perform a shallow clone to only fetch the specified branch.
-a shallow clone to only fetch the specified branch.
 
 #### Tag example
 
@@ -284,9 +283,9 @@ spec:
     commit: "<commit SHA>"
 ``` 
 
-This field takes precedence over all other fields. Using the [`go-git` Git
+This field takes precedence over all other fields. It can be combined with
-implementation](#git-implementation), it can be combined with `.spec.ref.branch`
+`.spec.ref.branch` to perform a shallow clone of the branch, in which the
-to perform a shallow clone of the branch, in which the commit must exist:
+commit must exist:
 
 ```yaml
 ---
@@ -385,32 +384,13 @@ resume.
 
 ### Git implementation
 
-**Note:** `libgit2` is being deprecated, as its use is known to cause controllers
+`.spec.gitImplementation` is deprecated and its value ignored, the git
-to panic when running over long periods of time, or when under high GC pressure.
+implementation used across Flux is go-git.
-A new opt-out feature gate `ForceGoGitImplementation` was introduced, which will
-use `go-git` regardless of the value defined at `.spec.gitImplementation`.
-This can be disabled by starting the controller with the additional flag below:
-`--feature-gates=ForceGoGitImplementation=false`.
-
-`.spec.gitImplementation` is an optional field to change the client library
-implementation used for Git operations (e.g. clone, checkout). The default
-value is `go-git`.
-
-Unless you need support for a specific Git wire protocol functionality not
-supported by the default implementation (as documented below), changing the
-implementation is generally not recommended as it can come with its own set of
-drawbacks. For example, not being able to make use of shallow clones forces the
-controller to fetch the whole Git history tree instead of a specific one,
-resulting in an increase of disk space and traffic usage.
-
-**Note:** The `libgit2` implementation does not support shallow clones or
-Git submodules.
 
 #### Optimized Git clones
 
 Optimized Git clones decreases resource utilization for GitRepository
-reconciliations. It supports both `go-git` and `libgit2` implementations
+reconciliations.
-when cloning repositories using branches or tags.
 
 When enabled, it avoids full Git clone operations by first checking whether
 the revision of the last stored artifact is still the head of the remote
@@ -428,20 +408,13 @@ not affected by this functionality.
 #### Proxy support
 
 When a proxy is configured in the source-controller Pod through the appropriate
-environment variables, for example `HTTPS_PROXY`, `NO_PROXY`, etc. There may be
+environment variables, for example `HTTPS_PROXY`, `NO_PROXY`, etc.
-some limitations in the proxy support based on the Git implementation.
-
-| Git Implementation | HTTP_PROXY | HTTPS_PROXY | NO_PROXY | Self-signed Certs |
-|--------------------|------------|-------------|----------|-------------------|
-| `go-git`           | true       | true        | true     | false             |n
-| `libgit2`          | true       | true        | true     | true              |
 
 ### Recurse submodules
 
 `.spec.recurseSubmodules` is an optional field to enable the initialization of
 all submodules within the cloned Git repository, using their default settings.
-This option is only available when using the (default) `go-git` [Git
+This option defaults to `false`.
-implementation](#git-implementation), and defaults to `false`.
 
 Note that for most Git providers (e.g. GitHub and GitLab), deploy keys can not
 be used as reusing a key across multiple repositories is not allowed. You have