Improve documentation of ink_storage::Mapping

[cmichi]

No description provided.

[paritytech-cicd-pr]

🦑 📈 ink! Example Contracts ‒ Changes Report 📉 🦑

⚠️ The ink! master is ahead of your branch, this might skew the comparison data below.

These are the results when building the examples/* contracts from this branch with cargo-contract 0.17.0-4195197 and comparing them to ink! master:

	Δ Optimized Size	Δ Used Gas	Total Optimized Size	Total Used Gas
accumulator			1.35 K
adder			2.47 K
contract-terminate			1.23 K	215_704
contract-transfer			8.47 K	15_704
delegator			6.86 K	50_833
dns			9.70 K	47_112
erc1155			28.12 K	94_224
erc20			9.34 K	47_112
erc721			13.17 K	125_632
flipper			1.63 K	15_704
incrementer			1.56 K	15_704
multisig			26.25 K	102_922
proxy			3.36 K	32_147
rand-extension			4.64 K	15_704
subber			2.48 K
trait-erc20			9.64 K	47_112
trait-flipper			1.41 K	15_704
trait-incrementer			1.54 K	31_408

Link to the run | Last update: Thu Feb 17 22:42:17 CET 2022

[codecov-commenter]

Codecov Report

Merging #1138 (e25ed7f) into master (e345679) will increase coverage by 0.05%.
The diff coverage is n/a.

❗ Current head e25ed7f differs from pull request most recent head af16409. Consider uploading reports for the commit af16409 to get more accurate results

@@            Coverage Diff             @@
##           master    #1138      +/-   ##
==========================================
+ Coverage   78.66%   78.72%   +0.05%     
==========================================
  Files         253      253              
  Lines        9411     9409       -2     
==========================================
+ Hits         7403     7407       +4     
+ Misses       2008     2002       -6     

Impacted Files	Coverage Δ
crates/storage/src/lazy/mapping.rs	54.28% <ø> (ø)
crates/primitives/src/key_ptr.rs	75.00% <0.00%> (-25.00%)	⬇️
crates/allocator/src/bump.rs	66.66% <0.00%> (+4.16%)	⬆️
crates/lang/ir/src/ir/item_impl/impl_item.rs	61.70% <0.00%> (+4.25%)	⬆️
...ates/storage/src/collections/hashmap/fuzz_tests.rs	100.00% <0.00%> (+4.25%)	⬆️

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