doc: add last step

docs/migration_guides/v0.10.2_to_v1.0.0_nearcore.md

@@ -9,6 +9,10 @@ Steps:
 First we update to `1.0.0-alpha.5` version, which contains [deprecation](https://github.com/near/borsh-rs/pull/206) of `BorshSerialize::try_to_vec` method.
 
 ```diff
+diff --git a/Cargo.toml b/Cargo.toml
+index f38e88411..1587f4131 100644
+--- a/Cargo.toml
++++ b/Cargo.toml
 -borsh = { version = "0.10.2", features = ["rc"] }
 +borsh = { version = "1.0.0-alpha.5", features = ["derive", "rc"] }
 ```
@@ -25,7 +29,7 @@ warning: use of deprecated method `borsh::BorshSerialize::try_to_vec`: use `bors
     = note: `#[warn(deprecated)]` on by default
 ```
 
-We choose to fix it at once, as this method is removed in `1.0.0-alpha.5` -> `1.0.0` transition completely 
+We choose to fix it at once, as this method is [removed](https://github.com/near/borsh-rs/pull/221) in `1.0.0-alpha.5` -> `1.0.0` transition completely 
 with following diff:
 
 ```diff
@@ -401,3 +405,14 @@ with similar fix.
 ## 10. errors  similar to previous ones, in `near-store`, `near-network` and `near-state-viewer` packages
 
 There was a bunch of `borsh::maybestd` imports, which got replaced by their direct from-`std` counterparts.
+
+## 11. finally, we update `borsh` version to `1.0.0`:
+
+```diff
+diff --git a/Cargo.toml b/Cargo.toml
+index f38e88411..1587f4131 100644
+--- a/Cargo.toml
++++ b/Cargo.toml
+-borsh = { version = "1.0.0-alpha.5", features = ["derive", "rc"] }
++borsh = { version = "1.0.0", features = ["derive", "rc"] }
+```