Rollup merge of #72071 - PankajChaudhary5:ErrorCode-E0687, r=davidtwco

Added detailed error code explanation for issue E0687 in Rust compiler.

Added proper error explanation for issue E0687 in the Rust compiler.
Error Code E0687

Sub Part of Issue #61137

r? @GuillaumeGomez

src/test/ui/in-band-lifetimes/E0687.stderr

@@ -24,3 +24,4 @@ LL |     fn bar(&self, x: fn(&'a u32)) {}
 
 error: aborting due to 4 previous errors
 
+For more information about this error, try `rustc --explain E0687`.

src/test/ui/in-band-lifetimes/E0687_where.stderr

@@ -12,3 +12,4 @@ LL | fn baz(x: &impl Fn(&'a u32)) {}
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0687`.