Website: use git grep to check OCaml ref + update absolute links

[dannywillems]

ripgrep was not working in the GH action. Locally, either by executing directly the script or by running gh act, the output of the bash script checking the OCaml refs was correctly working.
Running with set -euo pipefail requires to run git grep -l -E exp "**/*.rs", i.e. by surrounding with double quotes the pattern matching for the files, because we activated the strict mode for bash. In other words, running git grep -l -E exp **/*.rs won't work.

I'm suspecting an error in ripgrep, but I don't have time to investigate right now.

[github-actions]

OCaml Reference Validation Results

Repository: https://github.com/MinaProtocol/mina.git
Branch: compatible
Status: ✓ Validation passed

Click to see full validation output

Checking OCaml references against https://github.com/MinaProtocol/mina.git (branch: compatible)
Fetching current commit from compatible...
Current OCaml commit: 992ac748ae16347460bd4d5859b0c8b5ce26e847

Validating references...
========================
✓ VALID: ledger/src/scan_state/transaction_logic/for_tests.rs -> src/lib/transaction_logic/mina_transaction_logic.ml L:2285-2285
  ⚠ STALE COMMIT: 5da42ccd72e791f164d4d200cf1ce300262873b3 (current: 992ac748ae16347460bd4d5859b0c8b5ce26e847)
✓ VALID: ledger/src/scan_state/transaction_logic/for_tests.rs -> src/lib/transaction_logic/mina_transaction_logic.ml L:2351-2356
  ⚠ STALE COMMIT: 5da42ccd72e791f164d4d200cf1ce300262873b3 (current: 992ac748ae16347460bd4d5859b0c8b5ce26e847)
✓ VALID: ledger/src/scan_state/transaction_logic/for_tests.rs -> src/lib/transaction_logic/mina_transaction_logic.ml L:2407
  ⚠ STALE COMMIT: 5da42ccd72e791f164d4d200cf1ce300262873b3 (current: 992ac748ae16347460bd4d5859b0c8b5ce26e847)
✓ VALID: ledger/src/scan_state/transaction_logic/mod.rs -> src/lib/mina_base/transaction_status.ml L:9-51
  ⚠ STALE COMMIT: 5da42ccd72e791f164d4d200cf1ce300262873b3 (current: 992ac748ae16347460bd4d5859b0c8b5ce26e847)
✓ VALID: ledger/src/scan_state/transaction_logic/mod.rs -> src/lib/mina_base/transaction_status.ml L:452-454
  ⚠ STALE COMMIT: 5da42ccd72e791f164d4d200cf1ce300262873b3 (current: 992ac748ae16347460bd4d5859b0c8b5ce26e847)
✓ VALID: ledger/src/scan_state/transaction_logic/mod.rs -> src/lib/mina_base/with_status.ml L:6-10
  ⚠ STALE COMMIT: 5da42ccd72e791f164d4d200cf1ce300262873b3 (current: 992ac748ae16347460bd4d5859b0c8b5ce26e847)
✓ VALID: ledger/src/scan_state/transaction_logic/mod.rs -> src/lib/mina_base/fee_transfer.ml L:76-80
  ⚠ STALE COMMIT: 5da42ccd72e791f164d4d200cf1ce300262873b3 (current: 992ac748ae16347460bd4d5859b0c8b5ce26e847)
✓ VALID: ledger/src/scan_state/transaction_logic/mod.rs -> src/lib/mina_base/fee_transfer.ml L:68-69
  ⚠ STALE COMMIT: 5da42ccd72e791f164d4d200cf1ce300262873b3 (current: 992ac748ae16347460bd4d5859b0c8b5ce26e847)
✓ VALID: ledger/src/scan_state/transaction_logic/mod.rs -> src/lib/mina_base/coinbase.ml L:17-21
  ⚠ STALE COMMIT: 5da42ccd72e791f164d4d200cf1ce300262873b3 (current: 992ac748ae16347460bd4d5859b0c8b5ce26e847)

Summary
=======
Total references found: 9
Valid references: 9
Invalid references: 0
Stale commits: 9

⚠ Warning: 9 reference(s) have stale commits
Run with --update to update them automatically

[github-actions]

✓ Code Reference Verification Passed

All code references in the documentation have been verified successfully!

Total references checked: 1
Valid references: 1

The documentation is in sync with the codebase on the develop branch.