Fix 'not a hyperlink' doc warning

[tnull]

Fixes the following warning during cargo doc:

warning: this URL is not a hyperlink
  --> lightning/src/chain/chaininterface.rs:67:5
   |
67 | /// https://github.com/ElementsProject/lightning/commit/2e687b9b352c9092b5e8bd4a688916ac50b44af0
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://github.com/ElementsProject/lightning/commit/2e687b9b352c9092b5e8bd4a688916ac50b44af0>`
   |
   = note: `#[warn(rustdoc::bare_urls)]` on by default
   = note: bare URLs are not automatically turned into clickable links

[codecov-commenter]

Codecov Report

Merging #1624 (97e6682) into main (5023ff0) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #1624      +/-   ##
==========================================
- Coverage   90.82%   90.79%   -0.03%     
==========================================
  Files          80       80              
  Lines       44643    44643              
  Branches    44643    44643              
==========================================
- Hits        40547    40535      -12     
- Misses       4096     4108      +12     

Impacted Files	Coverage Δ
lightning/src/chain/chaininterface.rs	96.15% <ø> (ø)
lightning-net-tokio/src/lib.rs	76.85% <0.00%> (-0.31%)	⬇️
lightning/src/ln/functional_tests.rs	96.94% <0.00%> (-0.17%)	⬇️

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