[trivial]: Correct spellings across bips (bitcoin#675)

Co-authored-by: Mark "Murch" Erhardt <[email protected]>

Author: Varunram

bip-0035.mediawiki

@@ -16,7 +16,7 @@ Make a network node's transaction memory pool accessible via a new "mempool" mes
 
 ==Motivation==
 
-Several use cases make it desireable to expose a network node's transaction memory pool:
+Several use cases make it desirable to expose a network node's transaction memory pool:
 # SPV clients, wishing to obtain zero-confirmation transactions sent or received.
 # Miners, to avoid missing lucrative fees, downloading existing network transactions after a restart.
 # Remote network diagnostics.

bip-0080.mediawiki

@@ -35,7 +35,7 @@ Each level has a special meaning, described in the chapters below.
 
 ===Purpose===
 
-Purpose is a constant set following the BIP43 recommendation to: the ASCII value of "80" with the most signifigant bit set to indicate hardened derivation (0x80000050). It indicates that the subtree of this node is used according to this specification.
+Purpose is a constant set following the BIP43 recommendation to: the ASCII value of "80" with the most significant bit set to indicate hardened derivation (0x80000050). It indicates that the subtree of this node is used according to this specification.
 
 Hardened derivation is used at this level.
 

bip-0081.mediawiki

@@ -35,7 +35,7 @@ Each level has a special meaning, described in the chapters below.
 
 ===Purpose===
 
-Purpose is a constant set following the BIP43 recommendation to: the ASCII value of "81" with the most signifigant bit set to indicate hardened derivation (0x80000051). It indicates that the subtree of this node is used according to this specification.
+Purpose is a constant set following the BIP43 recommendation to: the ASCII value of "81" with the most significant bit set to indicate hardened derivation (0x80000051). It indicates that the subtree of this node is used according to this specification.
 
 Hardened derivation is used at this level.
 

bip-0174.mediawiki

@@ -800,7 +800,7 @@ A MIME type name will be added to this document once one has been registered.
 ==Extensibility==
 
 The Partially Signed Transaction format can be extended in the future by adding
-new types for key-value pairs. Backwards compatibilty will still be maintained as those new
+new types for key-value pairs. Backwards compatibility will still be maintained as those new
 types will be ignored and passed-through by signers which do not know about them.
 
 ===Version Numbers===