Add help target to the makefile

[philderbeast]

Fix#10596. Add help for some of the makefile targets.

$ make help
all Build the Cabal libraries and cabal-install executables.
checks Run all local checks; whitespace, style, and lint.
doctest-install Install doctest tool needed for running doctests.
doctest Run doctests.
exe Builds the cabal-install executables.
fix-whitespace Run fix-whitespace in fix mode.
ghcid-cli Run ghcid for the cabal-install executable.
ghcid-lib Run ghcid for the Cabal library.
help-banner Show the help banner.
help Show the commented targets.
init Set up git hooks and ignored revisions.
lib Builds the Cabal libraries.
lint-json Run HLint in JSON mode.
lint Run HLint.
style-commit Run the code styler on the previous commit.
style-modified Run the code styler on modified files.
style Run the code styler.
tags Generate editor tags, vim ctags and emacs etags.
users-guide Build the users guide.
users-guide-requirements Install the requirements for building the users guide.
whitespace Run fix-whitespace in check mode.

---

Template B: This PR does not modify behaviour or interface

E.g. the PR only touches documentation or tests, does refactorings, etc.

Include the following checklist in your PR:

• Patches conform to the coding conventions.
• Is this a PR that fixes CI? If so, it will need to be backported to older cabal release branches (ask maintainers for directions).

[philderbeast]

Label merge+no rebase is necessary when the pull request is from an organisation.

[philderbeast]

The help after #10603 was merged to master.

Tip

Should we switch from prefix/infix to suffix for fix, from -fix-* to *-fix, for the fixing targets?

@geekosaur, you chose the prefix name for fix-whitespace in 2858dc0 and that matches the tool name. On the other hand the lexical grouping works better with a suffix.

$ make help
all Build the Cabal libraries and cabal-install executables.
checks Run all local checks; whitespace, typos, style, and lint.
doctest-install Install doctest tool needed for running doctests.
doctest Run doctests.
exe Builds the cabal-install executables.
- fix-whitespace Run fix-whitespace in fix mode.
ghcid-cli Run ghcid for the cabal-install executable.
ghcid-lib Run ghcid for the Cabal library.
help-banner Show the help banner.
help Show the commented targets.
init Set up git hooks and ignored revisions.
lib Builds the Cabal libraries.
lint-json Run HLint in JSON mode.
lint Run HLint.
- markdown-fix-typos Fix typos in markdown files
markdown-typos Find typos in markdown files
+ markdown-typos-fix Fix typos in markdown files
style-commit Run the code styler on the previous commit.
style-modified Run the code styler on modified files.
style Run the code styler.
tags Generate editor tags, vim ctags and emacs etags.
typos-install Install typos-cli for typos target using cargo
users-guide Build the users guide.
- users-guide-fix-typos Fix typos in users guide
users-guide-requirements Install the requirements for building the users guide.
users-guide-typos Find typos in users guide
+ users-guide-typos-fix Fix typos in users guide
whitespace Run fix-whitespace in check mode.
+ whitespace-fix Run fix-whitespace in fix mode. 

[geekosaur]

There's also DevX vs. what makes the help text look better.

[philderbeast]

One thing I hadn't noted earlier is the number of groups with a common prefix that we have already:

• doctest → doctest + doctest-install
• ghcid → ghcid-cli + ghcid-lib
• lint → lint + lint-json
• style → style + style-commit + style-modified
• users-guide → users-guide + users-guide-requirements

We have could have common suffixes too; -install, -check and -fix.